The martensitic transformation,mechanical,and magnetic properties of the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) (x=0.125,0.25,0.375,0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5)[(x=0.125,y=0.125,0.25,0.375,0.5) and (x=0.125...The martensitic transformation,mechanical,and magnetic properties of the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) (x=0.125,0.25,0.375,0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5)[(x=0.125,y=0.125,0.25,0.375,0.5) and (x=0.125,0.25,0.375,y=0.625)]alloys were systematically studied by the first-principles calculations.For the formation energy,the martensite is smaller than the austenite,the Ni–(Co)–Mn–Cu–Ti alloys studied in this work can undergo martensitic transformation.The austenite and non-modulated (NM) martensite always present antiferromagnetic state in the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5) (y<0.625) alloys.When y=0.625 in the Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5) series,the austenite presents ferromagnetic state while the NM martensite shows antiferromagnetic state.Cu doping can decrease the thermal hysteresis and anisotropy of the Ni–(Co)–Mn–Ti alloy.Increasing Mn and decreasing Ti content can improve the shear resistance and normal stress resistance,but reduce the toughness in the Ni–Mn–Cu–Ti alloy.And the ductility of the Co–Cu co-doping alloy is inferior to that of the Ni–Mn–Cu–Ti and Ni–Co–Mn–Ti alloys.The electronic density of states was studied to reveal the essence of the mechanical and magnetic properties.展开更多
Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c...Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c. HEAs is generally low, significantly limiting their practical applications. Recently, the alloying of W has been evidenced to be able to remarkably improve the mechanical properties of f.c.c. HEAs and is becoming a hot topic in the community of HEAs. To date, when W is introduced, multiple strengthening mechanisms, including solid-solution strengthening, precipitation strengthening (μphase,σphase, and b.c.c. phase), and grain-refinement strengthening, have been discovered to be activated or enhanced. Apart from mechanical properties, the addition of W improves corrosion resistance as W helps to form a dense WO_(3) film on the alloy surface. Until now, despite the extensive studies in the literature, there is no available review paper focusing on the W doping of the f.c.c. HEAs. In that context, the effects of W doping on f.c.c. HEAs were reviewed in this work from three aspects, i.e., microstructure,mechanical property, and corrosion resistance. We expect this work can advance the application of the W alloying strategy in the f.c.c. HEAs.展开更多
Fe-Si ribbons and thin sheets with 6.5%Si content were prepared by means of the single roller rapid solidification and chemical vapor deposition (CVD), respectively. The initial textures of rapidly solidified Fe-6.5%S...Fe-Si ribbons and thin sheets with 6.5%Si content were prepared by means of the single roller rapid solidification and chemical vapor deposition (CVD), respectively. The initial textures of rapidly solidified Fe-6.5%Si ribbons were characteristic of the {100} fiber-type, which became weakened during primary recrystallization in various atmospheres. At the stage of secondary recrystallization, the {100} texture formed in Ar and the {110} texture in hydrogen, while there occurred a texture transformation from the {100} type to the {110} type in vacuum with the increase of annealing temperature. For Fe-6.5%Si sheets prepared by Si deposition in cold-rolled Fe-3%Si matrix sheets, their textures were dominated by the η-fiber (<001>//RD) with the maximum density at the {120}<001> orientations. After homogenization annealing, the η-fiber could evolve into the {130}<001> type or become more concentrated on the {120}<001> orientations, depending on the cold rolling modes of Fe-3%Si matrix sheets.展开更多
Fe62Cos-xCrxZr6Nb4B20 (x=0-4 at. pct) metallic glasses show high thermal stability with a maximum supercooled liquid region of about 84.8 K. The addition of 2 at. pct Cr causes the extension of the supercooled liqui...Fe62Cos-xCrxZr6Nb4B20 (x=0-4 at. pct) metallic glasses show high thermal stability with a maximum supercooled liquid region of about 84.8 K. The addition of 2 at. pct Cr causes the extension of the supercooled liquid region remarkably, leading to the enhancement of thermal stability and glass-forming ability. The crystallization of the Fe-based glassy alloys takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe, Fe2Zr and ZrB2. The long-range atomic rearrangements required for the precipitation of the multiple crystalline phases seem to play an important role in the appearance of the large supercooled liquid region through the retardation of the crystallization reactions. The Fe-based alloys exhibit soft ferromagnetic properties. The saturation magnetization decreases with increasing Cr content while the saturated magnetostriction increases as a function of Cr content. There is no distinct change in the saturation magnetization and coercive force with annealing temperature below the crystallization temperature. The devitrification gives rise to a considerable enhancement in both as and He.展开更多
The effects of Co and Fe co-doping Ni-Mn-In alloy on the phase stability,lattice parameters,mag-netic properties,and electronic structures are systematically investigated by using the first-principles calculations.Res...The effects of Co and Fe co-doping Ni-Mn-In alloy on the phase stability,lattice parameters,mag-netic properties,and electronic structures are systematically investigated by using the first-principles calculations.Results indicate that Fe atoms replace the excess Mn2 atoms by direct and indirect coex-istence(Fe→Mn 2 and Fe→In→Mn2);Co substitutes the Ni atoms by direct substitution(Co→Ni)for the Ni-Mn-In alloy.The austenites all exhibit the ferromagnetic(FM)state for the studied composi-tions.The NM martensites are in the ferrimagnetic(FIM-1)state for the Ni_(2)Mn_(1.5)In_(0.5),Ni_(2)Mn_(1.25)In_(0.5)Fe 0.25,Ni_(1.75)Mn_(1.5)In_(0.5)Co_(0.25),and Ni_(1.75)Mn_(1.25)In_(0.5)Co_(0.25)Fe 0.25 alloys,while the other compositions are in the FM state.The phase stability of austenite and martensite decreases with increasing Co and Fe co-doping.A magnetic-structural coupling transition occurs at x<0.25 and y<0.25.The Ni_(1.91)Mn_(1.5)In_(0.5)Co_(0.08)and Ni_(1.91)Mn_(1.42)In_(0.5)Co_(0.08)Fe_(0.08)alloys exhibit an A→6M→NM transformation,accompanied by a magnetic transition.When Co and Fe are co-doped,the hybridization strength between Co and Fe is greater than that between Co/Fe and Mn.The enhancement of magnetocaloric and elastocaloric effects is favored by larger magnetization difference(△M)and lattice volume change(△V/V_(0)).Based on the calculated phase stability,magneto-structure coupling,△V/V 0 and c/a ratio,one can predict that the Ni_(2)-x Mn_(1.5)-y In_(0.5)Co x Fe y alloy with Co content 0≤x≤0.25 and Fe content 0≤y≤0.05 is predicted to have good magneto-controlled functional behavior.展开更多
To expand the application of wire-arc additive manufacturing(WAAM)in aluminum alloy forming com-ponents,it is vitally important to reduce the porosity,refine microstructure,and thereby improve the mechanical propertie...To expand the application of wire-arc additive manufacturing(WAAM)in aluminum alloy forming com-ponents,it is vitally important to reduce the porosity,refine microstructure,and thereby improve the mechanical properties of the components.In this study,the interlayer friction stir processing(FSP)tech-nique was employed to assist the WAAM of 4043 Al-Si alloy,and the related effects on the microstruc-ture evolutions and mechanical properties of the fabricated builds were systematacially investigated.As compared to the conventional WAAM processing of Al-Si alloy,it was found that the introduction of in-terlayer FSP can effectively eliminate the pores,and both theα-Al dendrites and Si-rich eutectic network were severely broken up,leading to a remarkable enhancement in ductility and fatigue performance.The average yield strength(YS)and ultimate tensile strength(UTS)of the Al-based components produced by the combination of WAAM and interlayer FSP methods were 88 and 148 MPa,respectively.Meanwhile,the elongation(EL)of 37.5%and 28.8%can be achieved in the horizontal and vertical directions,respec-tively.Such anisotropy of EL was attributed to the inhomogeneous microstructure in the stir zone(SZ).Notably,the stress concentration can be effectively reduced by the elimination of porosity and Si-rich eu-tectic network fragmentation by the interlayer FSP,and thus the fatigue behavior was improved with the fatigue strength and elongation increased by∼28%and∼108.7%,respectively.It is anticipated that this study will provide a powerful strategy and theoretical guidance for the WAAM fabrication of Al-based alloy components with high ductility and fatigue performance.展开更多
A large adiabatic temperature change(△T_(ad))is a prerequisite for the application of elastocaloric refriger-ation.Theoretically,a large volume change ratio(△V/V_(0))during martensitic transformation is favorable to...A large adiabatic temperature change(△T_(ad))is a prerequisite for the application of elastocaloric refriger-ation.Theoretically,a large volume change ratio(△V/V_(0))during martensitic transformation is favorable to enhance△T_(ad).However,the design or prediction of△V/V_(0)in experiments is a complex task because the structure of martensite changes simultaneously when the lattice parameter of austenite is tuned by mod-ifying chemical composition.So far,the solid strategy to tailor△V/V_(0)is still urgently desirable.In this work,a first-principles-based method was proposed to estimate△V/V_(0)for Ni-Mn-based alloys.With this method,the substitution of Ga for In is found to be an effective method to increase the value of△V/V_(0)for Ni-Mn-In alloys.Combined with the strategies of reducing the negative contribution of magnetic en-tropy change(via the substitution of Cu for Mn)and introducing strong crystallographic texture(through directional solidification),an outstanding elastocaloric prototype alloy of Ni_(50)(Mn_(28.5)Cu_(4.5))(In_(14)Ga_(3))was fabricated experimentally.At room temperature,a huge△T_(ad)of-19 K and a large specific adiabatic temperature change of 67.8 K/GPa are obtained.The proposed first-principle-assisted framework opens up the possibility of efficiently tailoring△V/V_(0)to promote the design of advanced elastocaloric refrigerants.展开更多
The phase stability,magnetic properties,martensitic transformation,and electronic properties of the Ni_(2−x)Mn_(1+x+y)Sn_(1−y) system with excess Mn have been systematically investigated by the first-principles calcul...The phase stability,magnetic properties,martensitic transformation,and electronic properties of the Ni_(2−x)Mn_(1+x+y)Sn_(1−y) system with excess Mn have been systematically investigated by the first-principles calculations.Results indicate that the excess Mn atoms will directly occupy the sublattices of Ni(MnNi)or Sn(MnSn).The formation energy(Ef)of the austenite has a relationship with the Mn content:Ef=135.27(1+x+y)−293.01,that is,the phase stability of the austenite decreases gradually with the increase in Mn content.According to the results of the formation energy of austenite,there is an antiparallel arrangement of the magnetic moment between the excess and normal Mn atoms in the Ni_(2−x)Mn_(1+x+y)Sn_(1−y)(x=0 or y=0)system,while the magnetic moment direction of the normal Mn atoms arranges antiparallel to that of MnNi atoms and parallel to that of MnSn atoms in the Ni_(2−x)Mn_(1+x+y)Sn_(1−y)(x,y≠0)system.The martensitic transformation occurs in some Ni_(2−x)Mn_(1+x+y)Sn_(1−y)(x,y≠0)alloys with large magnetic moments of ferrimagnetic austenite.Besides,the valence electrons tend to distribute around the Ni or MnNi atoms and mainly bond with the normal Mn atoms.The results of this work can lay a theoretical foundation for further development of the Ni_(2−x)Mn_(1+x+y)Sn_(1−y) system as the potential ferromagnetic shape memory alloys.展开更多
Ti/Cu multilayered composites were fabricated via accumulative roll bonding(ARB). During codeformation of the constituent metals, the hard Ti layers necked preferentially and then fragmented with the development of sh...Ti/Cu multilayered composites were fabricated via accumulative roll bonding(ARB). During codeformation of the constituent metals, the hard Ti layers necked preferentially and then fragmented with the development of shear bands. Transmission electron microscopy showed that with increasing ARB cycles, grains in Ti were significantly refined even though dynamic recrystallization has occurred. For Cu the significant grain refinement was only found within the shear banded region when the composite was processed after five ARB cycles. Due to the diffusion of Cu atoms into Ti at the heterophase interfaces, amorphization with a width less than 10 nm was identified even in the composite processed by one cycle. At higher ARB cycles, the width of amorphous region increased and intermetallic compounds CuTi appeared from the region. The lattice defects introduced at the heterophase interfaces under roll bonding was responsible for the formation of the nano-scaled compounds. X-ray diffraction showed that an abnormal {1120} fiber texture was developed in Ti layers, while significant brass-type textures were developed in Cu layers. Some orientations along the {1120} fiber favored the prismatic < a> slip for Ti.Tensile tests revealed the elevated strength without a substantial sacrifice of ductility in the composites during ARB. The unique mechanical properties were attributed to the significantly refined grains in individual metals, the good bonding between the constituent metals, as well as the development of an abnormal {1120} fiber texture in Ti layers.展开更多
High-grade non-oriented silicon steel with higher permeability and lower core loss has become the pursed target with the rapid developnient of electrical machines.The effects of rare-earth(RE)element on recrystallizat...High-grade non-oriented silicon steel with higher permeability and lower core loss has become the pursed target with the rapid developnient of electrical machines.The effects of rare-earth(RE)element on recrystallization texture in RE-doped Fe-3.1 wt.%Si-1.2 wt.%Al non-oriented silicon steel were investigated by macro-and micro-texture analyses.Nonlinear variation of recrystallization texture with RE element content was observed.In the competition among main recrystallization texture components,favorable{113}<361>and X fiber(<001>//ND)are strengthened and unfavorable y fiber is evidently decreased by the addition of RE element,whereas the effect of RE element is reversed by excess RE element.The recrystallization texture development is determined by RE-affected nucleation and grain growth in terms of grain boundary migration related to segregation and inclusion.The properly inhibited grain boundary mobility can promote favorable recrystallization texture by the improved nucleation and efficient grain growth.展开更多
High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture ({ [10}(001)) of grain oriented (GO) silicon steel...High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture ({ [10}(001)) of grain oriented (GO) silicon steel during secondary recrystallization process, an in situ experiment using hi gh energy X-ray diffraction was designed. The results showed that the secondary recrystallization began when the heating temperature was 1,494 K, and the grains grew rapidly above this temperature. With an increase in annealing temperature, the large grains with 7 orientation [〈111〉//normal direction] formed and gradually occupied the dominant position. As the annealing temperature increased even further, the grains with Goss orientation to a very large size by devouring the 7 orientation grains that formed in the early annealing stage. A single crystal with a Goss orientation was observed in the GO silicon steel when the annealing temperature was 1,540 K.展开更多
The Ni43.75Mn37.5In12.5Co6.25 alloy was obtained by using the spark plasma sintering(SPS)technique.The martensitic transformation,magnetic and mechanical properties of the SPS alloy were investigated.Key findings demo...The Ni43.75Mn37.5In12.5Co6.25 alloy was obtained by using the spark plasma sintering(SPS)technique.The martensitic transformation,magnetic and mechanical properties of the SPS alloy were investigated.Key findings demonstrate that the martensitic transformation temperature of this alloy is about 10 K lower than that of the as-cast one.Both SPS and as-cast alloys show a 7 layered modulated martensite(7M)at room temperature.The compressive fracture strength and strain of the SPS alloy increase by 176.92%and 33.33%compared with the as-cast alloy,achieving 1440 MPa and 14%,respectively.The maximum magnetic entropy change Smis 17.1 J kg^(-1)K^(-1)for the SPS alloy at the magnetic field of 5 T.展开更多
Brittleness is a bottleneck hindering the applications of fruitful functional properties of Ni–Mn-based multiferroic alloys.Recently,experimental studies on B alloying shed new light on this issue.However,the knowled...Brittleness is a bottleneck hindering the applications of fruitful functional properties of Ni–Mn-based multiferroic alloys.Recently,experimental studies on B alloying shed new light on this issue.However,the knowledge related to B alloying is limited until now.More importantly,the mechanism of the improved ductility,which is intrinsically related to the chemical bond that is difficult to reveal by routine experiments,is still unclear.In this context,by first-principles calculations,the impact and the correlated mechanism of B alloying were systemically studied by investigating four alloying systems,i.e.,(Ni_(2-x)B_(x))MnGa,Ni_(2)(Mn_(1-x)B_(x))Ga,Ni_(2)Mn(Ga_(1-x)B_(x))and(Ni_(2)MnGa)_(1-x)B_(x).Results show that B prefers the direct occupation manner when it replaces Ni,Mn and Ga.For interstitial doping,B tends to locate at octahedral rather than tetrahedral interstice.Calculations show that the replacement of B for Ga can effectively improve(reduce)the inherent ductility(inherent strength)due to the weaker covalent strength of Ni(Mn)–B compared with Ni(Mn)–Ga.In contrast,B staying at octahedral interstice will lead to the formation of new chemical bonds between Ni(Mn)and B,bringing about a significantly improved strength and a greatly reduced ductility.Upon the substitutions for Ni and Mn,they affect both the inherent ductility and strength insignificantly.For phase transition,the replacement of B for Ga tends to destabilize the austenite,which can be understood in the picture of the band Jahn–Teller effect.Besides,the substitution for Ga would not lead to an obvious reduction of magnetization.展开更多
In this work,the B2 partial disordered structure of the austenitic parent phase,martensitic transformation,elastic and magnetic properties of the Ni8 Mn4+xTi4-x(x=0,1 and 2) Heusler alloys have been systematically inv...In this work,the B2 partial disordered structure of the austenitic parent phase,martensitic transformation,elastic and magnetic properties of the Ni8 Mn4+xTi4-x(x=0,1 and 2) Heusler alloys have been systematically investigated by the first-principles calculations.The preferential atomic occupation of B2 structure is one Ti atom exchange with the nearest neighboring Mn atom from the view of lowest energy principle.This disordered exchange sites(Mn-Ti) and the excess Mn atoms occupying the Ti sites(MnTi)could reduce the nearest Mn-Mn distance,resulting in the anti ferromagnetic state in the austenitic and martensitic phases of the alloys.The total magnetic moment of the alloy decreases with the increasing Mn content;it is ascribed to the antiferromagnetic magnetic moments of the excess Mn atoms.When x=0,the alloy does not undergo martensitic transformation since the austenite has absolute phase stability.The martensitic transformation will occur during cooling process for x=1 or 2,owing to the energy difference between the austenite and the martensite could provide the driving force for the phase transformation.The elastic properties of the cubic austenitic phase for the Ni2 MnTi alloy is calculated,and the results reveal the reason why Ni-Mn-Ti alloy has excellent mechanical properties.The origin of martensitic transformation and magnetic properties was discussed based on the electronic density of states.展开更多
The martensitic transformation,kinetics,elastic and magnetic properties of the Ni2-xMn1.5In0.5Cox(x=0-0.33)ferromagnetic shape memory alloys were investigated experimentally and theoretically by first-principles calcu...The martensitic transformation,kinetics,elastic and magnetic properties of the Ni2-xMn1.5In0.5Cox(x=0-0.33)ferromagnetic shape memory alloys were investigated experimentally and theoretically by first-principles calculations.First-principles calculations show that Co directly occupies the site of Ni sublattice,and Co atoms prefer to distribute evenly in the structure.The optimized lattice constants are consistent with the experimental results.The martensitic transformation paths are as follows:PA↔FA↔6MFIM↔NMFIM when 0≤x<0.25;PA↔FA↔6MFM↔NMFIM with 0.25≤x<0.3 and PA↔FA↔NMFM with 0.3≤x≤0.33 for Ni2-xMn1.5In0.5Cox(x=0-0.33)alloys.The fundamental reasons for the decrease of TM with increasing Co content are explained from the aspects of first-principles calculations and martensitic transformation kinetics.The component interval of the magnetostructural coupling is determined as 0≤x≤0.25 by first-principles calculations.Furthermore,the origin of the demagnetization effect during martensitic transformation is attributed to the shortening of the nearest neighboring distances for Ni-Ni(Co)and Mn-Mn.Combining the theoretical calculations with experimental results,it is verified that the TM of the Co6 alloy is near room temperature and its magnetization differenceM is 94.6 emu/g.Therefore,magnetic materials with high performance can be obtained,which may be useful for new magnetic applications.展开更多
We demonstrate giant elastocaloric effect and outstanding refrigeration capacity in a <0 0 1>A textured Ni_(50)Mn_(35)In_(13)Si_(2) alloy with large transformation entropy change △S_(tr) and low-hysteresis △T_...We demonstrate giant elastocaloric effect and outstanding refrigeration capacity in a <0 0 1>A textured Ni_(50)Mn_(35)In_(13)Si_(2) alloy with large transformation entropy change △S_(tr) and low-hysteresis △T_(hys). On unloading from a relatively low compressive stress of 300 MPa, giant adiabatic temperature variation △T_(ad) up to –17.7 K was realized. Moreover, large stress-induced entropy change △S_(σ) of 25.9 J kg^(–1)K^(–1) andgiant refrigeration capacity RC_(σ) of 1330 J kg^(–1) were achieved under the compressive stress of 300 MPa.Simultaneously achieving giant △T_(ad) and outstanding refrigeration capacity indicates that this alloy ispromising to be the candidate material for elastocaloric refrigeration.展开更多
The roller is one of the main parts of a high-pressure grinding roller, which is a type of highly efficient ore crushing equipment. Its working life is strongly affected by the materials used. In this paper, a new kin...The roller is one of the main parts of a high-pressure grinding roller, which is a type of highly efficient ore crushing equipment. Its working life is strongly affected by the materials used. In this paper, a new kind of roller material, the high-vanadium alloy steel (HVAS), was investigated. The results showed that the as-cast microstructures of the HVAS roller contained martensite, residual austenite, and alloy carbides. The HVAS sample quenched at 1,080 ℃ had a high hardness, and it had much higher compressive strength and abrasive wear resistance after tempering at 560 ℃ for 30 rain. The mechanical properties of the HVAS are more sufficient than the existing roller materials, which are feasible for larger machine design.展开更多
In this study, 3-mm-thick hot-extruded plates of A1-12.7Si-0.7Mg alloy were used to fabricate the joints welded by gas metal arc welding. Effects of the post-weld heat treatment include solid solution treatment, water...In this study, 3-mm-thick hot-extruded plates of A1-12.7Si-0.7Mg alloy were used to fabricate the joints welded by gas metal arc welding. Effects of the post-weld heat treatment include solid solution treatment, water quenching, and artificial aging treatment on the microstructure, and mechanical properties of the weld joints have been investigated. Results showed that the welded joints after solid solution and artificial aging exhibited the increases in yield strength of 166 MPa and ultimate tensile strength of 148 MPa, respectively. Based on the microstructural observations, the associated mechanisms were discussed.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51771044)the Natural Science Foundation of Hebei Province(No.E2019501061)+3 种基金the Performance subsidy fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(No.22567627H)the Fundamental Research Funds for the Central Universities(No.N2223025)the State Key Lab of Advanced Metals and Materials(No.2022-Z02)Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)。
文摘The martensitic transformation,mechanical,and magnetic properties of the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) (x=0.125,0.25,0.375,0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5)[(x=0.125,y=0.125,0.25,0.375,0.5) and (x=0.125,0.25,0.375,y=0.625)]alloys were systematically studied by the first-principles calculations.For the formation energy,the martensite is smaller than the austenite,the Ni–(Co)–Mn–Cu–Ti alloys studied in this work can undergo martensitic transformation.The austenite and non-modulated (NM) martensite always present antiferromagnetic state in the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5) (y<0.625) alloys.When y=0.625 in the Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5) series,the austenite presents ferromagnetic state while the NM martensite shows antiferromagnetic state.Cu doping can decrease the thermal hysteresis and anisotropy of the Ni–(Co)–Mn–Ti alloy.Increasing Mn and decreasing Ti content can improve the shear resistance and normal stress resistance,but reduce the toughness in the Ni–Mn–Cu–Ti alloy.And the ductility of the Co–Cu co-doping alloy is inferior to that of the Ni–Mn–Cu–Ti and Ni–Co–Mn–Ti alloys.The electronic density of states was studied to reveal the essence of the mechanical and magnetic properties.
基金financially supported by the National Key R&D Program of China (No.2021YFA1200203)the National Natural Science Foundation of China (Nos.51922026 and 51975111)+1 种基金the Fundamental Research Funds for the Central Universities (No.N2202015,N2002005,and N2105001)the 111 Project of China (No.BP0719037 and B20029)。
文摘Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c. HEAs is generally low, significantly limiting their practical applications. Recently, the alloying of W has been evidenced to be able to remarkably improve the mechanical properties of f.c.c. HEAs and is becoming a hot topic in the community of HEAs. To date, when W is introduced, multiple strengthening mechanisms, including solid-solution strengthening, precipitation strengthening (μphase,σphase, and b.c.c. phase), and grain-refinement strengthening, have been discovered to be activated or enhanced. Apart from mechanical properties, the addition of W improves corrosion resistance as W helps to form a dense WO_(3) film on the alloy surface. Until now, despite the extensive studies in the literature, there is no available review paper focusing on the W doping of the f.c.c. HEAs. In that context, the effects of W doping on f.c.c. HEAs were reviewed in this work from three aspects, i.e., microstructure,mechanical property, and corrosion resistance. We expect this work can advance the application of the W alloying strategy in the f.c.c. HEAs.
基金the National Natural Science Foundation of China (Grant No. 50671021) Program for New Century Excellent Talents in University (Grant No. NCET-06-0287).
基金This work was supported by the National Natural Science Foundation of China under Grant No.50130010, Pok Ying-Tung Education Foundation under Grant No. 71045 and the AFCRST under PRA MX 97-04.
文摘Fe-Si ribbons and thin sheets with 6.5%Si content were prepared by means of the single roller rapid solidification and chemical vapor deposition (CVD), respectively. The initial textures of rapidly solidified Fe-6.5%Si ribbons were characteristic of the {100} fiber-type, which became weakened during primary recrystallization in various atmospheres. At the stage of secondary recrystallization, the {100} texture formed in Ar and the {110} texture in hydrogen, while there occurred a texture transformation from the {100} type to the {110} type in vacuum with the increase of annealing temperature. For Fe-6.5%Si sheets prepared by Si deposition in cold-rolled Fe-3%Si matrix sheets, their textures were dominated by the η-fiber (<001>//RD) with the maximum density at the {120}<001> orientations. After homogenization annealing, the η-fiber could evolve into the {130}<001> type or become more concentrated on the {120}<001> orientations, depending on the cold rolling modes of Fe-3%Si matrix sheets.
基金the National Natural Science Foundation of China under Grant No. 50471075.
文摘Fe62Cos-xCrxZr6Nb4B20 (x=0-4 at. pct) metallic glasses show high thermal stability with a maximum supercooled liquid region of about 84.8 K. The addition of 2 at. pct Cr causes the extension of the supercooled liquid region remarkably, leading to the enhancement of thermal stability and glass-forming ability. The crystallization of the Fe-based glassy alloys takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe, Fe2Zr and ZrB2. The long-range atomic rearrangements required for the precipitation of the multiple crystalline phases seem to play an important role in the appearance of the large supercooled liquid region through the retardation of the crystallization reactions. The Fe-based alloys exhibit soft ferromagnetic properties. The saturation magnetization decreases with increasing Cr content while the saturated magnetostriction increases as a function of Cr content. There is no distinct change in the saturation magnetization and coercive force with annealing temperature below the crystallization temperature. The devitrification gives rise to a considerable enhancement in both as and He.
基金supported by the National Natural Science Foundation of China(No.51771044)Natural Science Foun-dation of Hebei Province(No.E2019501061)+2 种基金the Fundamental Research Funds for the Central Universities(No.N2023027)Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)the LiaoNing Revitalization Talents Program(No.XLYC1802023).
文摘The effects of Co and Fe co-doping Ni-Mn-In alloy on the phase stability,lattice parameters,mag-netic properties,and electronic structures are systematically investigated by using the first-principles calculations.Results indicate that Fe atoms replace the excess Mn2 atoms by direct and indirect coex-istence(Fe→Mn 2 and Fe→In→Mn2);Co substitutes the Ni atoms by direct substitution(Co→Ni)for the Ni-Mn-In alloy.The austenites all exhibit the ferromagnetic(FM)state for the studied composi-tions.The NM martensites are in the ferrimagnetic(FIM-1)state for the Ni_(2)Mn_(1.5)In_(0.5),Ni_(2)Mn_(1.25)In_(0.5)Fe 0.25,Ni_(1.75)Mn_(1.5)In_(0.5)Co_(0.25),and Ni_(1.75)Mn_(1.25)In_(0.5)Co_(0.25)Fe 0.25 alloys,while the other compositions are in the FM state.The phase stability of austenite and martensite decreases with increasing Co and Fe co-doping.A magnetic-structural coupling transition occurs at x<0.25 and y<0.25.The Ni_(1.91)Mn_(1.5)In_(0.5)Co_(0.08)and Ni_(1.91)Mn_(1.42)In_(0.5)Co_(0.08)Fe_(0.08)alloys exhibit an A→6M→NM transformation,accompanied by a magnetic transition.When Co and Fe are co-doped,the hybridization strength between Co and Fe is greater than that between Co/Fe and Mn.The enhancement of magnetocaloric and elastocaloric effects is favored by larger magnetization difference(△M)and lattice volume change(△V/V_(0)).Based on the calculated phase stability,magneto-structure coupling,△V/V 0 and c/a ratio,one can predict that the Ni_(2)-x Mn_(1.5)-y In_(0.5)Co x Fe y alloy with Co content 0≤x≤0.25 and Fe content 0≤y≤0.05 is predicted to have good magneto-controlled functional behavior.
文摘To expand the application of wire-arc additive manufacturing(WAAM)in aluminum alloy forming com-ponents,it is vitally important to reduce the porosity,refine microstructure,and thereby improve the mechanical properties of the components.In this study,the interlayer friction stir processing(FSP)tech-nique was employed to assist the WAAM of 4043 Al-Si alloy,and the related effects on the microstruc-ture evolutions and mechanical properties of the fabricated builds were systematacially investigated.As compared to the conventional WAAM processing of Al-Si alloy,it was found that the introduction of in-terlayer FSP can effectively eliminate the pores,and both theα-Al dendrites and Si-rich eutectic network were severely broken up,leading to a remarkable enhancement in ductility and fatigue performance.The average yield strength(YS)and ultimate tensile strength(UTS)of the Al-based components produced by the combination of WAAM and interlayer FSP methods were 88 and 148 MPa,respectively.Meanwhile,the elongation(EL)of 37.5%and 28.8%can be achieved in the horizontal and vertical directions,respec-tively.Such anisotropy of EL was attributed to the inhomogeneous microstructure in the stir zone(SZ).Notably,the stress concentration can be effectively reduced by the elimination of porosity and Si-rich eu-tectic network fragmentation by the interlayer FSP,and thus the fatigue behavior was improved with the fatigue strength and elongation increased by∼28%and∼108.7%,respectively.It is anticipated that this study will provide a powerful strategy and theoretical guidance for the WAAM fabrication of Al-based alloy components with high ductility and fatigue performance.
基金supported by the National Natural Science Foundation of China(Nos.51922026,51975111)the Fundamental Research Funds for the Central Universities(Nos.N2202015,N2230002,N2002021,N2105001)the 111 Project of China(Nos.BP0719037,B20029).
文摘A large adiabatic temperature change(△T_(ad))is a prerequisite for the application of elastocaloric refriger-ation.Theoretically,a large volume change ratio(△V/V_(0))during martensitic transformation is favorable to enhance△T_(ad).However,the design or prediction of△V/V_(0)in experiments is a complex task because the structure of martensite changes simultaneously when the lattice parameter of austenite is tuned by mod-ifying chemical composition.So far,the solid strategy to tailor△V/V_(0)is still urgently desirable.In this work,a first-principles-based method was proposed to estimate△V/V_(0)for Ni-Mn-based alloys.With this method,the substitution of Ga for In is found to be an effective method to increase the value of△V/V_(0)for Ni-Mn-In alloys.Combined with the strategies of reducing the negative contribution of magnetic en-tropy change(via the substitution of Cu for Mn)and introducing strong crystallographic texture(through directional solidification),an outstanding elastocaloric prototype alloy of Ni_(50)(Mn_(28.5)Cu_(4.5))(In_(14)Ga_(3))was fabricated experimentally.At room temperature,a huge△T_(ad)of-19 K and a large specific adiabatic temperature change of 67.8 K/GPa are obtained.The proposed first-principle-assisted framework opens up the possibility of efficiently tailoring△V/V_(0)to promote the design of advanced elastocaloric refrigerants.
基金financially supported by the National Natural Science Foundation of China(No.51771044)the Natural Science Foundation of Hebei Province(No.E2019501061)+2 种基金the Performance subsidy fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei(No.22567627H)the Fundamental Research Funds for the Central Universities(No.N2223025)the Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)。
文摘The phase stability,magnetic properties,martensitic transformation,and electronic properties of the Ni_(2−x)Mn_(1+x+y)Sn_(1−y) system with excess Mn have been systematically investigated by the first-principles calculations.Results indicate that the excess Mn atoms will directly occupy the sublattices of Ni(MnNi)or Sn(MnSn).The formation energy(Ef)of the austenite has a relationship with the Mn content:Ef=135.27(1+x+y)−293.01,that is,the phase stability of the austenite decreases gradually with the increase in Mn content.According to the results of the formation energy of austenite,there is an antiparallel arrangement of the magnetic moment between the excess and normal Mn atoms in the Ni_(2−x)Mn_(1+x+y)Sn_(1−y)(x=0 or y=0)system,while the magnetic moment direction of the normal Mn atoms arranges antiparallel to that of MnNi atoms and parallel to that of MnSn atoms in the Ni_(2−x)Mn_(1+x+y)Sn_(1−y)(x,y≠0)system.The martensitic transformation occurs in some Ni_(2−x)Mn_(1+x+y)Sn_(1−y)(x,y≠0)alloys with large magnetic moments of ferrimagnetic austenite.Besides,the valence electrons tend to distribute around the Ni or MnNi atoms and mainly bond with the normal Mn atoms.The results of this work can lay a theoretical foundation for further development of the Ni_(2−x)Mn_(1+x+y)Sn_(1−y) system as the potential ferromagnetic shape memory alloys.
基金financially supported by the National Natural Science Foundation of China(No.51571057)the Fundamental Research Funds for the Central Universities(No.N170204012)
文摘Ti/Cu multilayered composites were fabricated via accumulative roll bonding(ARB). During codeformation of the constituent metals, the hard Ti layers necked preferentially and then fragmented with the development of shear bands. Transmission electron microscopy showed that with increasing ARB cycles, grains in Ti were significantly refined even though dynamic recrystallization has occurred. For Cu the significant grain refinement was only found within the shear banded region when the composite was processed after five ARB cycles. Due to the diffusion of Cu atoms into Ti at the heterophase interfaces, amorphization with a width less than 10 nm was identified even in the composite processed by one cycle. At higher ARB cycles, the width of amorphous region increased and intermetallic compounds CuTi appeared from the region. The lattice defects introduced at the heterophase interfaces under roll bonding was responsible for the formation of the nano-scaled compounds. X-ray diffraction showed that an abnormal {1120} fiber texture was developed in Ti layers, while significant brass-type textures were developed in Cu layers. Some orientations along the {1120} fiber favored the prismatic < a> slip for Ti.Tensile tests revealed the elevated strength without a substantial sacrifice of ductility in the composites during ARB. The unique mechanical properties were attributed to the significantly refined grains in individual metals, the good bonding between the constituent metals, as well as the development of an abnormal {1120} fiber texture in Ti layers.
基金National Key R&D Program of China(Grant No.2016YFB0300305)National Natural Science Foundation of China(Grant Nos.51671049 and 51931002)the Postdoctoral Science Foundation of China(Grant No.2018M640257).
文摘High-grade non-oriented silicon steel with higher permeability and lower core loss has become the pursed target with the rapid developnient of electrical machines.The effects of rare-earth(RE)element on recrystallization texture in RE-doped Fe-3.1 wt.%Si-1.2 wt.%Al non-oriented silicon steel were investigated by macro-and micro-texture analyses.Nonlinear variation of recrystallization texture with RE element content was observed.In the competition among main recrystallization texture components,favorable{113}<361>and X fiber(<001>//ND)are strengthened and unfavorable y fiber is evidently decreased by the addition of RE element,whereas the effect of RE element is reversed by excess RE element.The recrystallization texture development is determined by RE-affected nucleation and grain growth in terms of grain boundary migration related to segregation and inclusion.The properly inhibited grain boundary mobility can promote favorable recrystallization texture by the improved nucleation and efficient grain growth.
基金supported by the Key Projects of the National Science & Technology Pillar Program (No. 2011BAE13B03)the Fundamental Research Funds for the Central Universities (No. N110502001)
文摘High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture ({ [10}(001)) of grain oriented (GO) silicon steel during secondary recrystallization process, an in situ experiment using hi gh energy X-ray diffraction was designed. The results showed that the secondary recrystallization began when the heating temperature was 1,494 K, and the grains grew rapidly above this temperature. With an increase in annealing temperature, the large grains with 7 orientation [〈111〉//normal direction] formed and gradually occupied the dominant position. As the annealing temperature increased even further, the grains with Goss orientation to a very large size by devouring the 7 orientation grains that formed in the early annealing stage. A single crystal with a Goss orientation was observed in the GO silicon steel when the annealing temperature was 1,540 K.
基金the National Natural Science Foundation of China(No.51771044)the Natural Science Foundation of Hebei Province(No.E2019501061)+2 种基金the Fundamental Research Funds for the Central Universities(No.N2023027)the Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)the Liao Ning Revitalization Talents Program(No.XLYC1802023)。
文摘The Ni43.75Mn37.5In12.5Co6.25 alloy was obtained by using the spark plasma sintering(SPS)technique.The martensitic transformation,magnetic and mechanical properties of the SPS alloy were investigated.Key findings demonstrate that the martensitic transformation temperature of this alloy is about 10 K lower than that of the as-cast one.Both SPS and as-cast alloys show a 7 layered modulated martensite(7M)at room temperature.The compressive fracture strength and strain of the SPS alloy increase by 176.92%and 33.33%compared with the as-cast alloy,achieving 1440 MPa and 14%,respectively.The maximum magnetic entropy change Smis 17.1 J kg^(-1)K^(-1)for the SPS alloy at the magnetic field of 5 T.
基金the National Natural Science Foundation of China(Grant No.51801020,51922026,51771044)the Fundamental Research Funds for the Central Universities(Grant No.N2002005,N2002021)+2 种基金the Liao Ning Revitalization Talents Program(Grant No.XLYC1802023)the Ph.D.Starting Foundation of Liaoning Province(Grant No.20180540115)Programme of Introducing Talents of Discipline Innovation to Universities(the 111 Project of China,No.BP0719037,B20029)。
文摘Brittleness is a bottleneck hindering the applications of fruitful functional properties of Ni–Mn-based multiferroic alloys.Recently,experimental studies on B alloying shed new light on this issue.However,the knowledge related to B alloying is limited until now.More importantly,the mechanism of the improved ductility,which is intrinsically related to the chemical bond that is difficult to reveal by routine experiments,is still unclear.In this context,by first-principles calculations,the impact and the correlated mechanism of B alloying were systemically studied by investigating four alloying systems,i.e.,(Ni_(2-x)B_(x))MnGa,Ni_(2)(Mn_(1-x)B_(x))Ga,Ni_(2)Mn(Ga_(1-x)B_(x))and(Ni_(2)MnGa)_(1-x)B_(x).Results show that B prefers the direct occupation manner when it replaces Ni,Mn and Ga.For interstitial doping,B tends to locate at octahedral rather than tetrahedral interstice.Calculations show that the replacement of B for Ga can effectively improve(reduce)the inherent ductility(inherent strength)due to the weaker covalent strength of Ni(Mn)–B compared with Ni(Mn)–Ga.In contrast,B staying at octahedral interstice will lead to the formation of new chemical bonds between Ni(Mn)and B,bringing about a significantly improved strength and a greatly reduced ductility.Upon the substitutions for Ni and Mn,they affect both the inherent ductility and strength insignificantly.For phase transition,the replacement of B for Ga tends to destabilize the austenite,which can be understood in the picture of the band Jahn–Teller effect.Besides,the substitution for Ga would not lead to an obvious reduction of magnetization.
基金supported financially by the National Natural Science Foundation of China (No.51771044)the Natural Science Foundation of Hebei Province (No.E2019501061)+2 种基金the Fundamental Research Funds for the Central Universities (No.N2023027)the Programme of Introducing Talents of Discipline Innovation to Universities 2.0 (the"111 Project"of China 2.0,No.BP0719037)the LiaoNing Revitalization Talents Program (No.XLYC1802023)。
文摘In this work,the B2 partial disordered structure of the austenitic parent phase,martensitic transformation,elastic and magnetic properties of the Ni8 Mn4+xTi4-x(x=0,1 and 2) Heusler alloys have been systematically investigated by the first-principles calculations.The preferential atomic occupation of B2 structure is one Ti atom exchange with the nearest neighboring Mn atom from the view of lowest energy principle.This disordered exchange sites(Mn-Ti) and the excess Mn atoms occupying the Ti sites(MnTi)could reduce the nearest Mn-Mn distance,resulting in the anti ferromagnetic state in the austenitic and martensitic phases of the alloys.The total magnetic moment of the alloy decreases with the increasing Mn content;it is ascribed to the antiferromagnetic magnetic moments of the excess Mn atoms.When x=0,the alloy does not undergo martensitic transformation since the austenite has absolute phase stability.The martensitic transformation will occur during cooling process for x=1 or 2,owing to the energy difference between the austenite and the martensite could provide the driving force for the phase transformation.The elastic properties of the cubic austenitic phase for the Ni2 MnTi alloy is calculated,and the results reveal the reason why Ni-Mn-Ti alloy has excellent mechanical properties.The origin of martensitic transformation and magnetic properties was discussed based on the electronic density of states.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.51771044,51431005 and 51801020)the Natural Science Foundation of Hebei Province(No.E2019501061 and E2019203364)+1 种基金the Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)the LiaoNing Revitalization Talents Program(Grant No.XLYC1802023).
文摘The martensitic transformation,kinetics,elastic and magnetic properties of the Ni2-xMn1.5In0.5Cox(x=0-0.33)ferromagnetic shape memory alloys were investigated experimentally and theoretically by first-principles calculations.First-principles calculations show that Co directly occupies the site of Ni sublattice,and Co atoms prefer to distribute evenly in the structure.The optimized lattice constants are consistent with the experimental results.The martensitic transformation paths are as follows:PA↔FA↔6MFIM↔NMFIM when 0≤x<0.25;PA↔FA↔6MFM↔NMFIM with 0.25≤x<0.3 and PA↔FA↔NMFM with 0.3≤x≤0.33 for Ni2-xMn1.5In0.5Cox(x=0-0.33)alloys.The fundamental reasons for the decrease of TM with increasing Co content are explained from the aspects of first-principles calculations and martensitic transformation kinetics.The component interval of the magnetostructural coupling is determined as 0≤x≤0.25 by first-principles calculations.Furthermore,the origin of the demagnetization effect during martensitic transformation is attributed to the shortening of the nearest neighboring distances for Ni-Ni(Co)and Mn-Mn.Combining the theoretical calculations with experimental results,it is verified that the TM of the Co6 alloy is near room temperature and its magnetization differenceM is 94.6 emu/g.Therefore,magnetic materials with high performance can be obtained,which may be useful for new magnetic applications.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51771048,52171005)the Liaoning Revitalization Talents Program(Nos.XLYC1907082,XLYC1907046,XLYC1802023).
文摘We demonstrate giant elastocaloric effect and outstanding refrigeration capacity in a <0 0 1>A textured Ni_(50)Mn_(35)In_(13)Si_(2) alloy with large transformation entropy change △S_(tr) and low-hysteresis △T_(hys). On unloading from a relatively low compressive stress of 300 MPa, giant adiabatic temperature variation △T_(ad) up to –17.7 K was realized. Moreover, large stress-induced entropy change △S_(σ) of 25.9 J kg^(–1)K^(–1) andgiant refrigeration capacity RC_(σ) of 1330 J kg^(–1) were achieved under the compressive stress of 300 MPa.Simultaneously achieving giant △T_(ad) and outstanding refrigeration capacity indicates that this alloy ispromising to be the candidate material for elastocaloric refrigeration.
基金supported by the National High Technology Research and Development Program (No. 2012AA03A508)Project of Science and Technology Plan of Shenyang City (No. F12-027-2-00)Project of Science and Technology Plan of Liaoning Province (No. LNSBQ4-2010921055)
文摘The roller is one of the main parts of a high-pressure grinding roller, which is a type of highly efficient ore crushing equipment. Its working life is strongly affected by the materials used. In this paper, a new kind of roller material, the high-vanadium alloy steel (HVAS), was investigated. The results showed that the as-cast microstructures of the HVAS roller contained martensite, residual austenite, and alloy carbides. The HVAS sample quenched at 1,080 ℃ had a high hardness, and it had much higher compressive strength and abrasive wear resistance after tempering at 560 ℃ for 30 rain. The mechanical properties of the HVAS are more sufficient than the existing roller materials, which are feasible for larger machine design.
基金financially supported by the Project of National Science & Technology Pillar Program (Nos.2009BAG12A07-B02 and 2009BAE80B01)National Natural Science Foundation of China (No.51071040)
文摘In this study, 3-mm-thick hot-extruded plates of A1-12.7Si-0.7Mg alloy were used to fabricate the joints welded by gas metal arc welding. Effects of the post-weld heat treatment include solid solution treatment, water quenching, and artificial aging treatment on the microstructure, and mechanical properties of the weld joints have been investigated. Results showed that the welded joints after solid solution and artificial aging exhibited the increases in yield strength of 166 MPa and ultimate tensile strength of 148 MPa, respectively. Based on the microstructural observations, the associated mechanisms were discussed.