Effect of heat treatment on microstructure and mechanical properties of Ti-containing low alloy martensitic wear-resistant steel

Effects of quenching temperature and cooling conditions(water cooling and 10%NaCl cooling)on microstructure and mechanical properties of a 0.2%Ti low alloy martensitic wear-resistant steel used for die casting ejector plate were investigated.The results show that lath martensite can be obtained after austenitizing in the range of 860-980℃and then water cooling.With an increase in austenitizing temperature,the precipitate content gradually decreases.The precipitates are mainly composed of TiC and Ti4C2S2,and their total content is between 1.15wt.%and 1.64wt.%.The precipitate phase concentration by water-cooling is higher than that by10%NaCl cooling due to the lower cooling rate of water cooling.As the austeniting temperature increases,the hardness and tensile strength of both water cooled and 10%NaCl cooled steels firstly increase and then decrease.The experimental steel exhibits the best comprehensive mechanical properties after being austenitized at 900℃,cooled by 10%NaCl,and then tempered at 200℃.Its hardness,ultimate tensile strength,and wear rate reach551.4 HBW,1,438.2 MPa,and 0.48×10^(-2)mg·m^(-1),respectively.

Tailoring bimodal grain structure of Mg-9Al-1Zn alloy for strength-ductility synergy:Co-regulating effect from coarse Al_(2)Y and submicron Mg_(17)Al_(12) particles

Grain boundary strengthening is an effective strategy for increasing mechanical properties of Mg alloys.However,this method offers limited strengthening in bimodal grain-structured Mg alloys due to the difficultly in increasing the volume fraction of fine grains while keeping a small grain size.Herein,we show that the volume fraction of fine grains(FGs,~2.5μm)in the bimodal grain structure can be tailored from~30 vol.%in Mg-9 Al-1 Zn(AZ91)to~52 vol.%in AZ91-1Y(wt.%)processed by hard plate rolling(HPR).Moreover,a superior combination of a high ultimate tensile strength(~405 MPa)and decent uniform elongation(~9%)is achieved in present AZ91-1Y alloy.It reveals that a desired bimodal grain structure can be tailored by the co-regulating effect from coarse Al_(2)Y particles resulting in inhomogeneous recrystallization,and dispersed submicron Mg_(17)Al_(12)particles depressing the growth of recrystallized grains.The findings offer a valuable insight in tailoring bimodal grain-structured Mg alloys for optimized strength and ductility.

Structure and Magnetic Property of Amorphous Fe-Ni Particles Prepared by Mechanical Alloying

The amorphous Fe 67.5 Ni 32.5 alloy particles have been prepared by mechanical alloying (MA) process of elemental powders. The crystallization is observed at temperature around 405°C by means of differential thermal analyzer. It is found that the coercivity H C and the effective magnetic anisotropy value of amorphous phase are not far from that of crystal phase. The magnetization behavior of amorphous and nanocrystalline samples prepared by mechanical alloying and milling process are quite similar, they obey 1/H law at middle high field and 1/H 2 at higher field. The 1/H field dependence is attributed to a large number of dislocations created during MA process. The studies on the 1/H 2 field dependence reveals that magnetization of Fe Ni ultrafine particles are governed predominantly by internal stress fields induced by MA process.

Microstructure and properties of mechanical alloying particles reinforced aluminum matrix composites prepared by semisolid stirring pouring method

Aluminum matrix composites reinforced with mechanical alloying particles(SiC_p) were fabricated by the semisolid stirring pouring method. The inf luence of mechanical alloying particles and Mg on the microstructure and mechanical properties of the composites was investigated by means of optical microscopy(OM), X-ray diffraction scanning(XRD), electron microscopy(SEM) and energy dispersive spectroscopy(EDS). Results show that the addition of Mg converts the agglomerate mechanical al oying particles in ZL101 matrix composites into dispersed distribution in ZL101-Mg matrix composites, large matrix grains into f ine equiaxed matrix grains, and eutectic phase into f ine particles. So the mechanical properties of ZL101-Mg matrix composites are better than those of ZL101 matrix composites. The mechanical properties of ZL101/ZL101-Mg matrix composites are gradually increased with the increase of the volume fraction of mechanical alloying particles. When the volume fraction of mechanical alloying particles is 3%, the Vickers hardness and ultimate tensile strength of the ZL101/ZL101-Mg matrix composites reach their maximum values.

The Role of Particles in Fatigue Crack Propagation of Aluminum Matrix Composites and Casting Aluminum Alloys

疲劳裂缝繁殖( FCP )行为被学习原文如此理解 roleof 在 10 wt % SiCp/A2024 composites 的粒子和在扔铝 alloyA356.The 结果的 Si 粒子证明一些粒子在高三角洲 K 在 SiCp/Al compositeseven 出现在破裂表面上区域，它显示裂缝原文如此在 matrixavoiding 以内主要宣传了粒子由于粒子和强壮的 particle/matrixinterface.In 的高力量扔铝合金， Si

Fabrication and Mechanical Properties of 2024 Aluminum Alloy Reinforced by FeNiCrCoAl_3 High Entropy Particles

This article mainly discussed bulk material prepared by powder metallurgy,and the commercial 2024 aluminum alloy powder and FeNiCrCoAl 3 high entropy alloy powder( both produced by argon gas atomization process) were ball-milled for different hours. The prepared powder was consolidated by hot extrusion method. The microstructures of the milled powder and bulk alloy were examined by X- Ray Diffraction( XRD), Scanning Electron Microscopy( SEM) and Transmission Electron Microscopy( TEM). The thermal stability was tested by differential scanning calorimetry( DSC). Mechanical properties of the extruded alloy were examined by Vickers hardness tester and mechanical testing machine. The results show that after milling,the mixed particle sizes and microstructures of the alloy powder change obviously. The compressive strength of the extruded alloy has reached 580 MPa under certain conditions of milling time and composition.

Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic–sulfuric acid anodizing processes of ZL114A aluminum alloys

The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were in- vestigated by optical microscopy （OM） and scanning electron microscopy （SEM）. The anodic oxidation was performed at 25℃ and a con- stant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the ap- proximate ranges of 10~20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

Formation mechanism of gradient-distributed particles and their effects on grain structure in 01420 Al-Li alloy

Fine-grained 01420 Al-Li alloy sheets were produced by thermo-mechanical processing based on the mechanism of particle stimulated nucleation of recrystallization.The thermo-mechanically processed sheets were observed to contain layers of different microstructures along the thickness.The precipitate behavior of the second phase particles and their effects on the distribution of dislocations and layered recrystallized grain structure were analyzed by optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and X-ray diffractometry(XRD).The formation mechanism of the gradient particles was discussed.The results show that after aging,a gradient distribution of large particles along the thickness is observed,the particles in the surface layer(SL) are distributed homogeneously,whereas those in the center layer(CL) are mainly distributed parallel to the rolling direction,and the volume fraction of the particles in the SL is higher than that in the CL.Subsequent rolling in the presence of layer-distributed particles results in a corresponding homogeneous distribution of highly strained regions in the SL and a banded distribution of them in CL,which is the main reason for the formation of layered grain structure along the thickness in the sheets.

Properties of Dispersion Casting of Y2O3 Particles in Hypo,Hyper and Eutectic Binary Al-Cu Alloys

In the present work,the dispersion casting of Y-2O-3 particles in aluminum-copper alloy was investigated in terms of microstructural changes with respect to Cu contents of 20 （hypo）,33 （eutectic） and 40 （hyper） wt pct by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）.For the fabrication of Al-Cu alloy dispersed Y-2O-3 ceramic particles,stir casting method was employed.In case of Al-20 wt pct Cu alloy （hypoeutectic）,SEM images revealed that primary Al was grown up in the beginning.After that,eutectic phase with well dispersed ceramic particles was formed.In case of eutectic composition,Y-2O-3 particles were uniformly dispersed in the matrix.When the Cu is added into Al up to 40 wt pct （hypereutectic）,primary phase was grown up without any Y-2O-3 ceramic particles in the early stage of solidification.Thereafter, eutectic phase was formed with well dispersed ceramic particles.It can be concluded that Y-2O-3 ceramic particles is mostly dispersed in case of eutectic composition in Al-Cu alloy.

Microstructure of Nanometer γ-(Fe,Ni) Alloy Particles and Their Optical and Microwave Properties

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅγ－（Ｆｅ，Ｎｉ）ａｌｏｙｐａｒｔｉｃｌｅｓｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄａｎｄｔｈｅｉｒｍｉｃｒｏｓｔｒｕｃｔｕｒｅ，ｏｐｔｉｃａｌａｎｄｍｉｃｒｏｗａｖｅｐｒｏｐｅｒｔｉｅｓｈａｖｅｂｅｅｎｉｎｖｅｓｔｉｇａｔｅ...

INFLUENCE OF DISPERSIVELY PRECIPITATED PARTICLES ON MARTENSITE MORPHOLOGY IN Fe-Ni-Co-Ti ALLOYS

The Martensite formed at low temperatures in Fe-Ni-Co-Ti alloys is featured as thin plate when the size of γ' dispersively precipitated particles was about 20—50 nm.The interface of martensite plate is not smooth.If the γ'particles are sized less than 5 nm,the thin plate martensite with thermoelastisity may be found at low temperatures,whi greater than 5 nm, intermittent martensite may occur,and the plate martensite increases both in size and quantity with the coarsening of the γ particles.The lenticular or butterfly martensite forms at low tem- peratures until the γ' particles are up to 10—5 nm.

Comparisons of particles thermal behavior between Fe-base alloy and boron carbide during plasma transferred-arc powder surfacing

Comparisons of particle’s thermal behavior between Fe base alloy and boron carbide in plasma transferred arc (PTA) space was made based on theoretical evaluation results in this article. It was found that most of the Fe base particles would be fully melted while they transporting through the central plasma field with 200 A surfacing currents. And the particles with a diameter less than 0.5×10 -4 m might be fully evaporated. However, for the boron carbide (B 4C) particles, only the one with a diameter less than 0.5×10 -4 m could be melted in the same PTA space. Most of B 4C particles are only preheated at its solid state when they were fed through the central field of PTA plasma when the surfacing current is equal to or less than 200 A . When the arc current was smaller than100 A , only the particles smaller than 0.5×10 -4 m could be melted in the PTA space for the Fe base alloy. Almost none of the discussed B 4C particles could be melted in the 100 A PTA space.

INFLUENCE OF DISPERSIVE Y_2O_3 PARTICLES ALLOYING BY LASER IRRADIATION ON OXIDATION BEHAVIOUR OF AN SUPERALLOY

The homogeneous dispersive Y2O3 particles were melt-doped on the surface of a superalloy by laser alloying and the effect of Y2O3 on the oxidation resistance of the alloy were investigated. The results showed that compact α-Al2O3 oxide scales formed continuously on the alloy surface and the internal oxidation was eliminated and oxidation rate decreased. Therefore, the oxidation resistanee of the alloy was improved.

Effect of TiO_(2)nano-ceramic particles on microstructure and mechanical properties of Al_(0.4)CoCrFe_(2)Ni_(2)high-entropy alloy

Al_(0.4)CoCrFe_(2)Ni_(2)high-entropy alloys with different additions of TiO_(2) nanoceramic particles(0,1.25vol.%,2.5vol.%,3.75vol.%and 5vol.%,respectively)were prepared by using the vacuum arc melting method.The effects of TiO_(2) addition on the crystal structure,microstructures and mechanical properties of the alloy were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile testing.The microstructure analysis shows that the TiO_(2)nano-ceramic particles added in the alloy are decomposed,and a small amount of Al_(2)O_(3)and a great number of intermetallic compounds(γ'phases)with simple cube structure are formed.Theγ'phases are enriched at inter-dendrite,which increases the resistance of dislocation movement during the deformation of the alloy,thus balancing the problem of high plasticity and low strength of the alloy.When the addition of TiO_(2)is 2.5vol.%,the strength of the high-entropy alloy reaches the maximum of 489 MPa,which is 11.1%higher than the matrix alloy composed of single FCC phase.

X-ray Diffraction Line Profile Broadening of Fe_(50)Pd_(50) Alloy Ultrafine Particles

The composition distribution in Fe50Pd50 alloy ultrafine particles prepared by inert gas condensation method was investigated in details by means of X-ray diffraction technique through deconvolution of the X-ray diffraction data. The microscopic composition distribution in the alloy UFP was identified, which is caused by nonuniformity of the melt, fractional distillation during the evaporation process and statistical fluctuation during nucleation and coalescence of the alloy particles. The composition distribution affects the properties of the alloy UFP

Propertices of Fe－Si alloy ultrafine particles pre－pared by the Gas－evaporation

ＰｒｏｐｅｒｔｉｃｅｓｏｆＦｅ－Ｓｉａｌｌｏｙｕｌｔｒａｆｉｎｅｐａｒｔｉｃｌｅｓｐｒｅ－ｐａｒｅｄｂｙｔｈｅＧａｓ－ｅｖａｐｏｒａｔｉｏｎＬｉＪｉａｎ￣１；ＸｕＪｉａｎｆｅｎｇ￣２；ＺｈｏｕＴｉｅｊｕｎ￣２；ＧｕｏＺａｉｂｉｎｇ￣２１（Ｄｅｐａｒｔ...

Effect of post annealing on phase transformation of Ni-Mn-Ga ferromagnetic shape memory alloy particles prepared by ball milling

The effect of post annealing on the phase transformation of Ni52Mn24Ga24 ferromagnetic shape memory alloy particles prepared by ball milling was studied. Ni52Mn24Ga24 alloy particles at micron scale were prepared successfully by ball milling the crushed bulk alloy. SEM observation reveals that the shape of the as-milled particle is regular polygon and a lot of cracks can be seen at the surface of the particles. For as-milled particles,the widening of characteristic peak can be found in the XRD pattern,and no transformation characterization can be detected by DSC. Post annealing at the elevated temperature will recover the transformation behavior of milled particles to the same level as that of bulk sample. It is shown that with increasing annealing temperature above 400 ℃,Ms decreases and As increases,while the magnetic transition temperature keeps constant. XRD results indicate that the change of grain size of the particles results in such an effect of post annealing.

Structural transition of Ni-Mn-Ga ferromagnetic shape memory alloy particles prepared by ball milling

The size,crystal structure and phase transformation of Ni49.8Mn28.5Ga21.7 alloy particles prepared by planetary ball milling(PBM) and vibration ball milling(VBM) were investigated by SEM,XRD and DSC. The results show that the particles milled by PBM for 4 h exhibit irregular polyhedron,with the size distribution between 5 μm and 40 μm. These particles present disordered fct structure with no phase transformation behaviour. When annealed at 600 ℃ for 1 h,the crystal structure of the particles evolves from disordered fct to Heusler completely. The particles milled by VBM for 4 h exhibit flaky shape,with the size distribution from 3 μm to 30 μm. The particles present disordered fcc structure with no phase transformation behaviour. However the crystal structure of these particles doesn't transform from disordered fcc to Heusler completely after annealing at 600 ℃ for 1 h,for the severe lattice distortion induced in the VBM process is not eliminated entirely.

MICROSTRUCTURES OF A NOVEL HIGH STRENGTH AND WEAR-RESISTING ZINC ALLOY

ＭＩＣＲＯＳＴＲＵＣＴＵＲＥＳＯＦＡＮＯＶＥＬＨＩＧＨＳＴＲＥＮＧＴＨＡＮＤＷＥＡＲ－ＲＥＳＩＳＴＩＮＧＺＩＮＣＡＬＬＯＹＬｉＹｕａｎｙｕａｎ；ＸｉａＷｅｉ；ＮｇａｉＴｕｎｇｗａｉＬｅｏ；ＬｕｏＪｕｎｍｉｎｇ；ＺｈｅｎｇＬｉｎｇｙｉ（Ｄｅｐａｒｔｍｅ...

Effect of particle size on the preparation and microwave absorption properties of FeSiAl magnetically soft alloy hollow microspheres

FeSiAl magnetically soft alloy hollow microspheres(MSAHMs) were prepared by self-reactive quenching technology based on Fe + Si + AI + KNO_3 reactive systems, in order to obtain absorbents with light weight, low frequency and high efficiency. Firstly, twice-balling adhesive precursor method was used to obtain FeSiAl magnetically soft alloy agglomerate powders. Then agglomerate powders with the mesh number of 150-240, 240-325 and 325-400 were sprayed through the flame field into the quenching water. At last, FeSiAl MSAHMs with coarse(average at 86.97 μm), medium(average at 52.16 μm) and fine particles(average at 31.80 μm) were got. Effect of particle size on the phases and microwave absorption properties in low frequency band was studied by XRD and vector network analyzer. The results show that,Fe_3 Si_(0.7)Al_(0.3) and Fe_3 Si_(0.5)Al_(0.5) appear in the phase components of FeSiAl MSAHMs,which is important to improve the microwave absorption properties in low frequency. In addition, the real part(ε′) and imaginary part(ε″) of complex permittivity, the real part(μ′) and imaginary part(μ″) of complex permeability of FeSiAl MSAHMs all present the trend of fine particles > medium particles > coarse particles. The microwave absorption properties in low frequency are improved with the increasing of particle size, and the absorption peak moves to lower frequency range. The properties of fine particles are the best. Their matching thickness of samples is at 5 mm, and the minimum reflectivity is-43 dB at this thickness. The absorption frequency band lower than-10 dB is 4.6-7.6 GHz with a bandwidth of 3 GHz.