There have been many interesting studies on high-entropy alloys(HEAs), also known as multi-component(MC) alloys(MCAs), in recent years. MC metallic-glasses(MGs) have shown the potential to express the advantag...There have been many interesting studies on high-entropy alloys(HEAs), also known as multi-component(MC) alloys(MCAs), in recent years. MC metallic-glasses(MGs) have shown the potential to express the advantages of MCAs and MGs in tandem. Amorphous phase formation rules are a crucial issue in the HEA and MCA field. For equal or near-equal atomic ratio alloys, mixed-entropy among the elements has a significant effect on the phase formation. This paper focuses on HEA amorphous phase formation rules. In the first two sections, the recent progress in amorphous phase formation in HEAs and MCAs is reviewed, including the effective factors and correlative parameters related to amorphous phase formation. In the third section, novel MCMGs including high-entropy(HE) bulk-metallic-glass(HE-BMG) and MCMG films developed in recent decades are summarized, and the giant-magnetic-impedance(GMI) effect of MC amorphous fibers is discussed.展开更多
New refractory high-entropy alloys,CrHfNbTaTi and CrHfMoTaTi,derived from the well-known HfNbTaTiZr alloy through principal element substitution were prepared using vacuum arc melting.The phase components,microstructu...New refractory high-entropy alloys,CrHfNbTaTi and CrHfMoTaTi,derived from the well-known HfNbTaTiZr alloy through principal element substitution were prepared using vacuum arc melting.The phase components,microstructures,and compressive properties of the alloys in the as-cast state were investigated.Results showed that both alloys were composed of BCC and cubic Laves phases.In terms of mechanical properties,the yield strength increased remarkably from 926 MPa for HfNbTaTiZr to 1258 MPa for CrHfNbTaTi,whereas a promising plastic strain of around 15.0%was retained in CrHfNbTaTi.The morphology and composition of the network-shaped interdendritic regions were closely related to the improved mechanical properties due to elemental substitution.Dendrites were surrounded by an incompact interdendritic shell after Mo incorporation,which deteriorated yield strength and accelerated brittleness.展开更多
A binder phase of TiO based cermets, a kind of imitated gold materials, was developed by adding active element Si to Fe-Cr alloy, and the related mechanisms were studied. The wettability, matching in thermodynamics an...A binder phase of TiO based cermets, a kind of imitated gold materials, was developed by adding active element Si to Fe-Cr alloy, and the related mechanisms were studied. The wettability, matching in thermodynamics and interracial strength were investigated by the high temperature sessile drop method and element area scanning. The linear expansion coefficients of the materials were measured using TAH100 thermal analyzer. The results show that the wettability of Fe-Cr alloy on TiO are small, with a wetting angle about 90°. After adding some Si in Fe-Cr alloy, its wetting angle can be decreased to about 25°, the interracial reactions can be prevented effectively and high interface binding can be formed. Fe-25% Cr-1.5% Si matches the thermal expansion coefficient of TiO, so it is a kind of relatively perfect binder for TiO based cermets imitated gold.展开更多
The effect of trace amount of active element Si on the wetting and interface characteristics of 1Cr18Ni11Nb/TiO was investigated. Based on the results, a new binder phase for TiO based cermets imitated gold materials ...The effect of trace amount of active element Si on the wetting and interface characteristics of 1Cr18Ni11Nb/TiO was investigated. Based on the results, a new binder phase for TiO based cermets imitated gold materials was developed, and the related mechanisms were studied. The results indicated that there was small wet-ability of the 1Cr18Ni11Nb alloy on TiO, and the interface binding strength of 1Cr18Ni11Nb/TiO was low. 1.5%Si in 1Cr18Ni11Nb could not only make the alloy wet TiO, but also lead to mutual dissolving near the interface, forming high interface binding strength and matching with the thermal expansion coefficient of TiO.展开更多
Thiswork aims to explore WC-G201 high entropy cemented carbides properties fabricated by spark plasma sintering with AlCoCrFeNiTi_(0.2)and WC as binder phase and hard phase respectively.AlCoCrFeNiTi_(0.2)powder and WC...Thiswork aims to explore WC-G201 high entropy cemented carbides properties fabricated by spark plasma sintering with AlCoCrFeNiTi_(0.2)and WC as binder phase and hard phase respectively.AlCoCrFeNiTi_(0.2)powder and WC powder were mixed at the mass ratio of 5:95,10:90 and 15:85 respectively,and then via SPS at 1300℃for 5min.The results show that the binder phase has good wettability to WC,and with the increase of binder phase content,the hardness of the alloy decreases gradually,fracture toughness increases first and then decreases,the maximum value is 7.88 MPa m1/2.It is estimated that the comprehensive mechanical property of cemented carbides is the best when the binder content is between 5wt%and 10wt%.展开更多
The low-cost Fe-Cu,Fe-Ni,and Cu-based high-entropy alloys exhibit a widespread utilization prospect.However,these potential applications have been limited by their low strength.In this study,a novel Fe_(31)Cu_(31)Ni_(...The low-cost Fe-Cu,Fe-Ni,and Cu-based high-entropy alloys exhibit a widespread utilization prospect.However,these potential applications have been limited by their low strength.In this study,a novel Fe_(31)Cu_(31)Ni_(28)Al_(4)Ti_(3)Co_(3) immiscible high-entropy alloy(HEA)was developed.After vacuum arc melting and copper mold suction casting,this HEA exhibits a unique phase separation microstructure,which consists of striped Cu-rich regions and Fe-rich region.Further magnification of the striped Cu-rich region reveals that it is composed of a Cu-rich dot-like phase and a Fe-rich region.The aging alloy is further strengthened by a L1_(2)-Ni_(3)(AlTi)nanoprecipitates,achieving excellent yield strength(1185 MPa)and uniform ductility(~8.8%).The differential distribution of the L1_(2) nanoprecipitate in the striped Cu-rich region and the external Fe-rich region increased the strength difference between these two regions,which increased the strain gradient and thus improved hetero-deformation induced(HDI)hardening.This work provides a new route to improve the HDI hardening of Fe-Cu alloys.展开更多
Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase ...Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase to BCC phase with the increase of Al content.The stable phase of FeCoNiCrCu0.5Alx high-entropy alloys will transform from FCC phase to FCC+BCC duplex phases when x value increases from 0.5 to 1.5.The hardness of BCC phase is higher than that of FCC phase,and the corrosion resistance of BCC phase is better than FCC phase in chlorine ion and acid medium.High hardness and good corrosion resistance can be obtained in as-cast FeCoNiCrCu0.5Al1.0 alloy.展开更多
The micro-cracking behaviors of two high-entropy alloys(HEAs) of the FeMnCoCrNi family prepared by selective laser melting were systematically studied. Residual stresses were also analyzed by X-ray diffraction techniq...The micro-cracking behaviors of two high-entropy alloys(HEAs) of the FeMnCoCrNi family prepared by selective laser melting were systematically studied. Residual stresses were also analyzed by X-ray diffraction technique. Results show that the equiatomic FeMnCoCrNi HEAs with a relatively stable single-phase face-centered cubic(FCC) structure suffered from micro-cracking with residual tensile stress after laser melting. In contrast, the metastable non-equiatomic Fe MnCoCr HEAs with reduced stacking fault energy are free of micro-cracks with residual compressive stress at various volumetric energy densities(VEDs). The displacive transformation from the FCC matrix to the hexagonal close-packed(HCP) phase during cooling prevents the micro-cracking via consuming thermal stress related internal energy. Further, the displacive transformation during tensile deformation contributes to the higher strength and ductility of the metastable dual-phase HEA compared to that of the stable single-phase HEA. These findings provide useful guidance for the design of strong, ductile, and crack-free alloys for additive manufacturing by tuning phase stability.展开更多
The alloying behavior and microstructures of the(CoCrFeNiMn)_(90)M_(10)(M=Al,Hf)high-entropy alloy(HEA)powders fabricated by mechanical alloying were studied.The CoCrFeNiMn)_(90)Al_(10) powders have duplex solid-solut...The alloying behavior and microstructures of the(CoCrFeNiMn)_(90)M_(10)(M=Al,Hf)high-entropy alloy(HEA)powders fabricated by mechanical alloying were studied.The CoCrFeNiMn)_(90)Al_(10) powders have duplex solid-solution structures.In contrast,nanocrystalline HfNi_(3) anchoring in amorphous structures is found in the(CoCrFeNiMn)_(90)Hf_(10) powders.The(CoCrFeNiMn)_(90)Al_(10) powders show better ferromagnetic behaviors,mainly explained by the facilitated motion of the magnetic domain induced by the coherent interface between duplex phases.Combined with our previous work,the rules of forming solid-solution and amorphous phase in as-milled HEA powders are preliminarily proposed.It is found that,compared with the as-cast HEA reported previously,the variation range of mixing enthalpy with atomic size difference of the solid-solution formed in as-milled HEA powders is broader.Moreover,the variation ranges between mixing enthalpy and entropy with atomic size difference of the amorphous phase in HEA powder become wider than those of high-entropy bulk metallic glass.展开更多
In the face of the requirement that nuclear fusion reactor materials exhibit more excellent thermal,mechanical and physical properties,a novel refractory highentropy alloy,WTaHfTiZr was proposed.The constituent elemen...In the face of the requirement that nuclear fusion reactor materials exhibit more excellent thermal,mechanical and physical properties,a novel refractory highentropy alloy,WTaHfTiZr was proposed.The constituent elements were selected in consideration of low activation,high melting point and high thermostability.The alloys were prepared by arc melting.The as-cast alloy shows a dendrite microstructure with two disordered BCC phases,which caused by the preferential nucleation of W and Ta with much higher melting points during solidification.It exhibits a high compressive yield strength of 1,900 MPa and fracture strain of 8.1% at room temperature,and its yield strengths are up to 612 MPa at 700 ℃ and 203 MPa at 1,000 ℃,respectively.The high strengths are attributed mainly to solid solution strengthening and second phase strengthening.This alloy shows great promise as one of the next-generation nuclear fusion reactor materials.展开更多
High-entropy alloys(HEAs)generally possess complex component combinations and abnormal properties.The traditional methods of investigating these alloys are becoming increasingly inefficient because of the unpredictabl...High-entropy alloys(HEAs)generally possess complex component combinations and abnormal properties.The traditional methods of investigating these alloys are becoming increasingly inefficient because of the unpredictable phase transformation and the combination of many constituents.The development of compositionally complex materials such as HEAs requires high-throughput experimental methods,which involves preparing many samples in a short time.Here we apply the high-throughput method to investigate the phase evolution and mechanical properties of novel HEA film with the compositional gradient of(Cr,Fe,V)-(Ta,W).First,we deposited the compositional gradient film by co-sputtering.Second,the mechanical properties and thermal stability of the(Cr0.33Fe0.33V0.33)x(Ta0.5W0.5)100−x(x=13-82)multiplebased-elemental(MBE)alloys were investigated.After the deposited wafer was annealed at 600℃for 0.5 h,the initial amorphous phase was transformed into a body-centered cubic(bcc)structure phase when x=33.Oxides were observed on the film surface when x was 72 and 82.Finally,the highest hardness of as-deposited films was found when x=18,and the maximum hardness of annealed films was found when x=33.展开更多
The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are compos...The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are composed of the single FCC phase.The BCC and B2 phases are found.It is confirmed that the BCC phase in the Al7Cr20Fe66Ni7 alloy is transformed from the FCC phase at about 900℃ during cooling.While in the 800℃-annealed Al7Cr20Fe60Ni13 alloy,the FCC phase is stable and the hardness decreases.After annealing at 1000℃,for the precipitation of the B2 particles,the Al content in the FCC phase decreases,which results in decreasing of the alloy hardness.Moreover,after annealing at 800℃,a small amount of Al-rich B2 particles precipitate at the phase boundary and some nanocrystal BCC phase precipitates in the FCC matrix,which increases the hardness of the Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=41−49)alloys.These results will help to the composition design and processing design of the Al−Cr−Fe−Ni based high-entropy alloys.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51471025)
文摘There have been many interesting studies on high-entropy alloys(HEAs), also known as multi-component(MC) alloys(MCAs), in recent years. MC metallic-glasses(MGs) have shown the potential to express the advantages of MCAs and MGs in tandem. Amorphous phase formation rules are a crucial issue in the HEA and MCA field. For equal or near-equal atomic ratio alloys, mixed-entropy among the elements has a significant effect on the phase formation. This paper focuses on HEA amorphous phase formation rules. In the first two sections, the recent progress in amorphous phase formation in HEAs and MCAs is reviewed, including the effective factors and correlative parameters related to amorphous phase formation. In the third section, novel MCMGs including high-entropy(HE) bulk-metallic-glass(HE-BMG) and MCMG films developed in recent decades are summarized, and the giant-magnetic-impedance(GMI) effect of MC amorphous fibers is discussed.
基金supported by the National Natural Science Foundation of China(No.51604173)the Natural Science Foundation of Jiangsu Higher Education Institution of China(No.18KJB430012)。
文摘New refractory high-entropy alloys,CrHfNbTaTi and CrHfMoTaTi,derived from the well-known HfNbTaTiZr alloy through principal element substitution were prepared using vacuum arc melting.The phase components,microstructures,and compressive properties of the alloys in the as-cast state were investigated.Results showed that both alloys were composed of BCC and cubic Laves phases.In terms of mechanical properties,the yield strength increased remarkably from 926 MPa for HfNbTaTiZr to 1258 MPa for CrHfNbTaTi,whereas a promising plastic strain of around 15.0%was retained in CrHfNbTaTi.The morphology and composition of the network-shaped interdendritic regions were closely related to the improved mechanical properties due to elemental substitution.Dendrites were surrounded by an incompact interdendritic shell after Mo incorporation,which deteriorated yield strength and accelerated brittleness.
文摘A binder phase of TiO based cermets, a kind of imitated gold materials, was developed by adding active element Si to Fe-Cr alloy, and the related mechanisms were studied. The wettability, matching in thermodynamics and interracial strength were investigated by the high temperature sessile drop method and element area scanning. The linear expansion coefficients of the materials were measured using TAH100 thermal analyzer. The results show that the wettability of Fe-Cr alloy on TiO are small, with a wetting angle about 90°. After adding some Si in Fe-Cr alloy, its wetting angle can be decreased to about 25°, the interracial reactions can be prevented effectively and high interface binding can be formed. Fe-25% Cr-1.5% Si matches the thermal expansion coefficient of TiO, so it is a kind of relatively perfect binder for TiO based cermets imitated gold.
文摘The effect of trace amount of active element Si on the wetting and interface characteristics of 1Cr18Ni11Nb/TiO was investigated. Based on the results, a new binder phase for TiO based cermets imitated gold materials was developed, and the related mechanisms were studied. The results indicated that there was small wet-ability of the 1Cr18Ni11Nb alloy on TiO, and the interface binding strength of 1Cr18Ni11Nb/TiO was low. 1.5%Si in 1Cr18Ni11Nb could not only make the alloy wet TiO, but also lead to mutual dissolving near the interface, forming high interface binding strength and matching with the thermal expansion coefficient of TiO.
文摘Thiswork aims to explore WC-G201 high entropy cemented carbides properties fabricated by spark plasma sintering with AlCoCrFeNiTi_(0.2)and WC as binder phase and hard phase respectively.AlCoCrFeNiTi_(0.2)powder and WC powder were mixed at the mass ratio of 5:95,10:90 and 15:85 respectively,and then via SPS at 1300℃for 5min.The results show that the binder phase has good wettability to WC,and with the increase of binder phase content,the hardness of the alloy decreases gradually,fracture toughness increases first and then decreases,the maximum value is 7.88 MPa m1/2.It is estimated that the comprehensive mechanical property of cemented carbides is the best when the binder content is between 5wt%and 10wt%.
基金Projects(52001083,52171111,U2141207)supported by the National Natural Science Foundation of ChinaProject(LH2020E060)supported by the Natural Science Foundation of Heilongjiang,China。
文摘The low-cost Fe-Cu,Fe-Ni,and Cu-based high-entropy alloys exhibit a widespread utilization prospect.However,these potential applications have been limited by their low strength.In this study,a novel Fe_(31)Cu_(31)Ni_(28)Al_(4)Ti_(3)Co_(3) immiscible high-entropy alloy(HEA)was developed.After vacuum arc melting and copper mold suction casting,this HEA exhibits a unique phase separation microstructure,which consists of striped Cu-rich regions and Fe-rich region.Further magnification of the striped Cu-rich region reveals that it is composed of a Cu-rich dot-like phase and a Fe-rich region.The aging alloy is further strengthened by a L1_(2)-Ni_(3)(AlTi)nanoprecipitates,achieving excellent yield strength(1185 MPa)and uniform ductility(~8.8%).The differential distribution of the L1_(2) nanoprecipitate in the striped Cu-rich region and the external Fe-rich region increased the strength difference between these two regions,which increased the strain gradient and thus improved hetero-deformation induced(HDI)hardening.This work provides a new route to improve the HDI hardening of Fe-Cu alloys.
基金Project(NCET-11-0127) supported by the Program for New Century Excellent Talents in University,ChinaProject supported by the Fundamental Research Funds for the Central Universities,China
文摘Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase to BCC phase with the increase of Al content.The stable phase of FeCoNiCrCu0.5Alx high-entropy alloys will transform from FCC phase to FCC+BCC duplex phases when x value increases from 0.5 to 1.5.The hardness of BCC phase is higher than that of FCC phase,and the corrosion resistance of BCC phase is better than FCC phase in chlorine ion and acid medium.High hardness and good corrosion resistance can be obtained in as-cast FeCoNiCrCu0.5Al1.0 alloy.
基金financial support of the National Natural Science Foundation of China (51505166,51971248)the Huxiang Young Talents Project (2018RS3007,2019RS1001)+1 种基金the Innovation-Driven Project of Central South University,China (2020CX023)Science and Technology Project of Hunan Province (2020GK2031)。
文摘The micro-cracking behaviors of two high-entropy alloys(HEAs) of the FeMnCoCrNi family prepared by selective laser melting were systematically studied. Residual stresses were also analyzed by X-ray diffraction technique. Results show that the equiatomic FeMnCoCrNi HEAs with a relatively stable single-phase face-centered cubic(FCC) structure suffered from micro-cracking with residual tensile stress after laser melting. In contrast, the metastable non-equiatomic Fe MnCoCr HEAs with reduced stacking fault energy are free of micro-cracks with residual compressive stress at various volumetric energy densities(VEDs). The displacive transformation from the FCC matrix to the hexagonal close-packed(HCP) phase during cooling prevents the micro-cracking via consuming thermal stress related internal energy. Further, the displacive transformation during tensile deformation contributes to the higher strength and ductility of the metastable dual-phase HEA compared to that of the stable single-phase HEA. These findings provide useful guidance for the design of strong, ductile, and crack-free alloys for additive manufacturing by tuning phase stability.
基金financial supports from the National Natural Science Foundation of China (No.51971102)the Major Basic Research Projects of Shandong Natural Science Foundation,China (No.ZR2020ZD06)+1 种基金the Open Research Fund of Songshan Lake Materials Laboratory,China (No.2021SLABFK08)the Science and Technology Program of University of Jinan,China (No.XKY2117)。
文摘The alloying behavior and microstructures of the(CoCrFeNiMn)_(90)M_(10)(M=Al,Hf)high-entropy alloy(HEA)powders fabricated by mechanical alloying were studied.The CoCrFeNiMn)_(90)Al_(10) powders have duplex solid-solution structures.In contrast,nanocrystalline HfNi_(3) anchoring in amorphous structures is found in the(CoCrFeNiMn)_(90)Hf_(10) powders.The(CoCrFeNiMn)_(90)Al_(10) powders show better ferromagnetic behaviors,mainly explained by the facilitated motion of the magnetic domain induced by the coherent interface between duplex phases.Combined with our previous work,the rules of forming solid-solution and amorphous phase in as-milled HEA powders are preliminarily proposed.It is found that,compared with the as-cast HEA reported previously,the variation range of mixing enthalpy with atomic size difference of the solid-solution formed in as-milled HEA powders is broader.Moreover,the variation ranges between mixing enthalpy and entropy with atomic size difference of the amorphous phase in HEA powder become wider than those of high-entropy bulk metallic glass.
基金financially supported by the National Natural Science Foundation of China (Grant Nos.51971099 and 52071088)
文摘In the face of the requirement that nuclear fusion reactor materials exhibit more excellent thermal,mechanical and physical properties,a novel refractory highentropy alloy,WTaHfTiZr was proposed.The constituent elements were selected in consideration of low activation,high melting point and high thermostability.The alloys were prepared by arc melting.The as-cast alloy shows a dendrite microstructure with two disordered BCC phases,which caused by the preferential nucleation of W and Ta with much higher melting points during solidification.It exhibits a high compressive yield strength of 1,900 MPa and fracture strain of 8.1% at room temperature,and its yield strengths are up to 612 MPa at 700 ℃ and 203 MPa at 1,000 ℃,respectively.The high strengths are attributed mainly to solid solution strengthening and second phase strengthening.This alloy shows great promise as one of the next-generation nuclear fusion reactor materials.
基金the National Natural Science Foundation of China(No.51671020)the Fundamental Research Funds for the Central Universities(No.FRF-MP-19-013).
文摘High-entropy alloys(HEAs)generally possess complex component combinations and abnormal properties.The traditional methods of investigating these alloys are becoming increasingly inefficient because of the unpredictable phase transformation and the combination of many constituents.The development of compositionally complex materials such as HEAs requires high-throughput experimental methods,which involves preparing many samples in a short time.Here we apply the high-throughput method to investigate the phase evolution and mechanical properties of novel HEA film with the compositional gradient of(Cr,Fe,V)-(Ta,W).First,we deposited the compositional gradient film by co-sputtering.Second,the mechanical properties and thermal stability of the(Cr0.33Fe0.33V0.33)x(Ta0.5W0.5)100−x(x=13-82)multiplebased-elemental(MBE)alloys were investigated.After the deposited wafer was annealed at 600℃for 0.5 h,the initial amorphous phase was transformed into a body-centered cubic(bcc)structure phase when x=33.Oxides were observed on the film surface when x was 72 and 82.Finally,the highest hardness of as-deposited films was found when x=18,and the maximum hardness of annealed films was found when x=33.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51771035,51671037)Natural Science Foundation of Jiangsu Province,China(BK20161190)the Priority Academic Program of Jiangsu Higher Education Institutions,China.
文摘The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are composed of the single FCC phase.The BCC and B2 phases are found.It is confirmed that the BCC phase in the Al7Cr20Fe66Ni7 alloy is transformed from the FCC phase at about 900℃ during cooling.While in the 800℃-annealed Al7Cr20Fe60Ni13 alloy,the FCC phase is stable and the hardness decreases.After annealing at 1000℃,for the precipitation of the B2 particles,the Al content in the FCC phase decreases,which results in decreasing of the alloy hardness.Moreover,after annealing at 800℃,a small amount of Al-rich B2 particles precipitate at the phase boundary and some nanocrystal BCC phase precipitates in the FCC matrix,which increases the hardness of the Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=41−49)alloys.These results will help to the composition design and processing design of the Al−Cr−Fe−Ni based high-entropy alloys.