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Enhancing the mechanical properties of casting eutectic high -entropy alloys via W addition

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International Journal of Minerals,metallurgy and Materials 2024年第6期31卷 1364-1372页

作者： Xu Yang Dezhi Chen Li Feng Gang Qin Shiping Wu Ruirun Chen national key laboratory for precision hot processing of metals School of Material Science and EngineeringHarbin Institute of TechnologyHarbin 150001China

The effect of W element on the microstructure evolution and mechanical properties of Al_(1.25)CoCrFeNi3 eutectic high-entropy alloy and Al_(1.25)CoCrFeNi_(3-x)W_(x)(x=0,0.05,0.1,0.3,and 0.5;atomic ratio)high-entropy alloys(HEAs)were explored.Results show that the Al_(1.25)CoCrFeNi_(3-x)W_(x) HEAs are composed of face-centered cubic and body-centered cubic(BCC)phases.As W content increases,the microstructure changes from eutectic to dendritic.The addition of W lowers the nucleation barrier of the BCC phase,decreases the valence electron concentration of the HEAs,and replaces Al in the BCC phase,thus facilitating the nucleation of the BCC phase.Tensile results show that the addition of W greatly improves the mechanical properties,and solid-solution,heterogeneous-interface,and second-phase strengthening are the main strengthening mechanisms.The yield strength,tensile strength,and elongation of the Al_(1.25)CoCrFeNi2.95W0.05 HEA are 601.44 MPa,1132.26 MPa,and 15.94%,respectively,realizing a balance between strength and plasti-city.The fracture mode of the Al_(1.25)CoCrFeNi_(3-x)W_(x) HEAs is ductile–brittle mixed fracture,and the crack propagates and initiates in the BCC phase.The eutectic lamellar structure impedes crack propagation and maintains plasticity.

关键词： high-entropy alloy microstructure mechanical property fracture behavior

Microstructures and mechanical properties of laser-directed energy deposited CrCoNi medium-entropy alloy

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Rare metals 2024年第7期43卷 3286-3300页

作者： Wen-Jie Zhao Chang-Yu Liu Peng-Cheng Che Zhi-Liang Ning Hong-Bo Fan Jian-Fei Sun Yong-Jiang Huang Alfonso H.W.Ngan national key laboratory for precision hot processing of metals Harbin Institute of Technology Space Environment Simulation Research Infrastructure Harbin Institute of Technology Department of Mechanical Engineering The University of Hong Kong

The distinctive intrinsic heat treatment(IHT)originating from cyclic reheating in the laser-directed energy deposition(LDED) has attracted growing attention in recent years.In this investigation,simulations and experimental characterizations were performed to examine the impact of IHT on the micros true ture and mechanical properties of LDED-fabricated CrCoNi medium-entropy alloy(MEA).The results show that the intensity of the IHT is proportional to the utilized laser energy density(LED).As the LED increased,significant dynamic recrystallization and grain refinement occurred within the alloy due to the enhanced intensity of IHT.However,the high LED leads to severe hot cracking within the as-built MEA,resulting in inferior ductility.By decreasing LED,the hot cracking was effectively eliminated.Meanwhile,low LED weakened the intensity of IHT and consequently inhibited kinetic conditions of dynamic recrystallization,resulting in a heterogeneous grain structure characterized by multi-scale-sized grains.This structure provides significant hetero-deformation-induced hardening during plastic deformation,enabling the alloy to have a sustainable work-hardening capacity.We expect that this work will have implications in taking full advantage of the unique IHT of the LDED process to fabricate ME As with excellent metallurgical quality and mechanical performance.

关键词： Intrinsic heat treatment Laser-directed energy deposition CrCoNi MEA Dynamic recrystallization Heterogeneous grain structure

Fabrication,Microstructure and Mechanical Properties of in situ GNPs Reinforced Magnesium Matrix Composites

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Acta metallurgica Sinica(English Letters) 2024年第3期37卷 561-569页

作者： Peitang Zhao Xuejian Li Hailong Shi Xiaoshi Hu Chunlei Zhang Chao Xu Xiaojun Wang The 38th Research Institute of China Electronics Technology Group Corporation Hefei 230088China national key laboratory of precision hot processing of metal Harbin Institute of TechnologyHarbin 150001China

Graphene reinforced magnesium matrix composites have wide applications in automotive,electronics,aerospace and military fields due to the fascinating mechanical properties.However,it is difficult to realize the high strength and ductility simultaneously.In this work,the in situ liquid-state method was utilized to prepare GNPs/Mg6Zn composites via CO_(2)/Mg chemical reaction.Tensile strength of the GNPs/Mg6Zn composites was improved with increasing content of the GNPs.Meantime,the composites also exhibit a notable plastic deformation stage,and especially the ductility of 0.12 GNPs/Mg6Zn composites reaches 27.6%.Therefore,this novel preparation method has great potential application for fabricating Mg matrix composites with high strength and high ductility.

关键词： Magnesium matrix composite In situ composite Microstructure Mechanical properties

Introduction of rare-earth element Sc in alloy design to modify wear features of dual-phase high-entropy alloy

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Rare metals 2024年第2期43卷 817-828页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung Chiu Shi-Ping Wu Jing-Jie Guo Guo national key laboratory for precision hot processing of metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin150001China School of metallurgy and Materials University of BirminghamBirminghamB152TTUK

Tailoring the alloy composition,which induces the hard secondary phase to increase hardness and strength to improve the wear features,is a feasible approach for developing wear-resistant metal materials.Here,a group of(AlCoCrFeNi)_(100–x)Sc_(x)(x=0–2.0,at%)high-entropy alloys(HEAs)are designed and the phase compositions and wear behaviors are explored.Sc-doped HEA series contain the primary body-centered cubic(BCC)and eutectic phases,in which the eutectic phase is composed of the alternately grown BCC and Laves phases.Sc addition promotes the diffusion of Ni atoms from BCC phase to form the Sc-rich Laves phase at the grain boundaries.Vickers hardness increases due to solid solution strengthening and second phase strengthening.And the second phase strengthening plays a more significant role relative to solid solution strengthening.Laves phase and the oxides caused by wear heating prevent the direct contact between friction pair and HEAs,thus inducing a decreased wear rate from 6.82×10^(−5) to 3.47×10^(−5)m^(3)·N^(−1)·m^(−1).Moreover,the wear mechanism changes from adhesive wear,abrasive wear and oxidative wear to abrasive wear and oxidative wear.

关键词： High entropy alloy(HEA) Laves phase Hardness Wear mechanism

A Hf-doped dual-phase high-entropy alloy: phase evolution and wear features

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Rare metals 2024年第1期43卷 324-333页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung Chiu Shi-Ping Wu Jing-Jie Guo national key laboratory for precision hot processing of metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China School of metallurgy and Materials University of BirminghamEdgbastonBirmingham B152TTUK

Initially defined high entropy alloys(HEAs)usually exhibit a single-phase solid-solution structure.However,two and/or more types of phases in HE As possibly induce the desired microstructure features,which contribute to improving the wear properties of HE As.Here,we prepare a series of(AlCoCrFeNi)_(100-x)Hf_(x)(x=0,2,4and 6;at%) HEAs and concern their phase compositions,micro structures and wear properties.Hf leads to the formation of(Ni,Co)_(2)Hf-type Laves phase and tailors the microstructure from a body-centered cubic(BCC) singlephase structure to a hypoeutectic structure.An increased hardness from~HV 512.3 to~HV 734.1 is due to solid-solution strengthening,grain refinement strengthening and precipitated phase strengthening.And a few oxides(Al_(2)O_(3)+Cr_(2)O_(3)) caused by the wear heating contribute to an 85.5% decrease in wear rate of the HEA system from6.71×10^(-5) to 0.97×10^(-5) m^(3)·N^(-1)·m^(-1).In addition,Hf addition changes the wear mechanism from abrasive wear,mild oxidative wear and adhesive wear to oxidative wear and adhesive wear.

关键词： High entropy alloy Laves phase Hardness Wear mechanism

Synergistic enhancement on mechanical properties and corrosion resistance of biodegradable Mg-Zn-Y alloy via V-microalloying

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Journal of Magnesium and Alloys 2024年第2期12卷 530-545页

作者： Jiaxin Zhang Xin Ding Ruirun Chen Wenchao Cao Jinshan Zhang Rui Zhao national key laboratory for precision hot processing of metals Harbin Institute of TechnologyNo.92West Dazhi StreetHarbinHeilongjiang 150001China College of Materials Science and Engineering Taiyuan University of TechnologyNo.79West Yingze StreetTaiyuanShanxi 030024China

For the sake of improving the mechanical properties and corrosion resistance of biodegradable Mg alloy synergistically,various content of element V(0,0.05,0.10,0.15,0.20 wt.%)are introduced into an Mg-Zn-Y alloy with long-period stacking ordered(LPSO)structure,and the effects of V on its microstructure,mechanical properties and corrosion resistance are investigated systematically.The results indicate that the grains are effectively refined by V addition,and the primaryα-Mg in Mg-Zn-Y-V0.1 alloy is most significantly refined,with grain size being decreased by 62%.The amount of 18R LPSO structure is increased owing to the V addition.The growth mode of the second phase(W-phase and 18R LPSO structure)is transformed to divorced growth pattern,which ascribes to the thermodynamic drive force of V to promote the nucleation of LPSO phase.Thus,18R LPSO structure presents a continuous distribution.Due to grains refinement and modification of second phase,the tensile strength and strain of alloys are both enhanced effectively.Especially,the ultimate tensile strength and the elongation of V0.1 alloy are 254 MPa and 15.26%,which are 41%and 61%higher than those of V-free alloy,respectively.Owing to the continuously distributed 18R LPSO structure with refined grains and stable product film,the weight loss and hydrogen evolution corrosion rates of V0.1 alloy are 7.1 and 6.2 mmy^(-1),respectively,which are 42.6%and 45.4%lower than those of V-free alloy.

关键词： Corrosion Mechanical property V-microalloying LPSO SKPFM

Phase transition of multi-component(TiZrVNb)C ceramics—Part II:From single phase to multiple phases via adjusting V content

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Journal of Advanced Ceramics 2024年第5期13卷 689-698页

作者： Qingyi Kong Lei Chen Sijia Huo Kunxuan Li Wenyu Lu Yujin Wang Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China key laboratory of Advanced Structure‒Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China national key laboratory of precision hot processing of metals Harbin Institute of TechnologyHarbin 150001China

To address the relatively mediocre mechanical properties of single-phase multi-component carbide ceramics,a phase transition from a single phase to multiple phases was proposed to achieve superior mechanical properties.A series of(TiZrVxNb)C0.8 ceramics with different V contents were fabricated by spark plasma sintering(SPS).The influence of the V content on the phase composition,microstructural evolution,and mechanical properties was investigated in detail.The transition behavior from a single phase to multiple phases is discovered and discussed.The formation of the Zr-rich phase and Zr-poor phase can be attributed to the increase in lattice distortion and mixed enthalpy caused by the addition of V.A nanometer lamellar structure with a semi-coherent interface obtained via in situ decomposition is reported for the first time in multi-component carbide ceramics.The semi-coherent interfaces with high dislocation density and strain concentration effectively improve the mechanical properties,grain refinement,and multi-phase formation.The optimal comprehensive mechanical properties of the Vickers hardness(26.3 GPa),flexural strength(369 MPa),and fracture toughness(3.1 MPa·m1/2)were achieved for the sample with 20 mol%V.

关键词： multi-component ceramics multiple phases microstructure evolution phase decomposition mechanical properties

EBSD analysis of grain boundary evolution and dynamic recrystallization of Inconel 625 superalloy at various hot spinning feed rates

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Progress in Natural Science:Materials International 2024年第1期34卷 56-65页

作者： Zhanjie Jing Jiangkun Fan Xudong Liu Yuelin Song Zixiao Wang Kai Cao Yuetan Chen Heng Fu Jianing Zhang Jinshan Li State key laboratory of Solidification processing Northwestern Polytechnical University Chongqing Innovation Center Northwestern Polytechnical University national&Local Joint Engineering Research Center for precision Thermoforming Technology of Advanced metal Materials

hot spinning can make the material withstand shear stress, so that the shape of the material has a great change,which is one of the main processing methods of nickel-based alloy plate members. Inconel 625 alloy, which has excellent high temperature mechanical properties and can be used as the main candidate material for aerospace applications, needs further study on its hot spinning deformation behavior and deformation mechanism. In this paper, the effect of feed rate on the microstructure evolution of Inconel 625 superalloy was studied by the electron backscattered diffraction technology. The microstructure with necklace-like structures composed of dynamic recrystallization(DRX) grains was observed after hot spinning. It was found that at the low feed rate, the promotion of DRX degree and grain refinement happened, where the grain size reached the trough of 10.99 μm under a feed rate of 300 mm/min. However, with the further feed rate rising, the degree of DRX was suppressed to a certain extent and grain size increased to 14.26 μm. On balance, the feed rate of 300 mm/min was the most efficient condition for grain refinement. Besides, it was revealed that both discontinuous dynamic recrystallization(DDRX) and continuous dynamic recrystallization(CDRX) occurred during hot spinning. DDRX includes the initial grain boundary nucleation by bulging and the annealing twin boundary assisted nucleation, while the CDRX mechanism is related to the continuous subgrain rotation within the deformed grain. DDRX is the main DRX mechanism.

关键词： Inconel 625 superalloy hot spinning Grain boundary evolution DRX mechanism

Phase transition of multi-component(TiZrVNb)C ceramics—Part I:Phase decomposition induced by carbon content

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Journal of Advanced Ceramics 2024年第5期13卷 679-688页

作者： Qingyi Kong Rao Zhang Lei Chen Sijia Huo Wenyu Lu Yujin Wang Boxin Wei Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China key laboratory of Advanced Structure‒Function Integrated Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150001China national key laboratory of precision hot processing of metals Harbin Institute of TechnologyHarbin 150001China

Phase decomposition can effectively enhance the mechanical properties of carbide ceramics and can overcome the difficulty of enhancing the mechanical properties of single-phase multicomponent carbide ceramics.In this work,a series of nonstoichiometric(TiZrVNb)Cx ceramics were prepared by spark plasma sintering(SPS)at different temperatures.The effects of the carbon content on the phase composition,microstructure evolution,and mechanical properties were investigated in detail.Phase decomposition occurred with decreasing carbon content.Two different solid solutions of(Ti,V)-rich and Zr-rich phases formed from the decomposition of equimolar single-phase solid solutions,namely,the Zr-poor phase and Zr-rich phase,respectively.The distribution of Nb element is relatively uniform.The semicoherent interfaces between the Zr-poor phase and the Zr-rich phase can harden and strengthen effectively under the synergistic effect of grain refinement.Ceramics with phase decomposition structures have apparent advantages compared to single-phase high-entropy carbides.This work provides an important train of thought for the microstructure tailoring and properties optimization of multi-component carbide ceramics.

关键词： multicomponent ceramics nontoichiometry microstructure evolution phase decomposition mechanical properties