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金属学报（英文版）
金属学报（英文版）

双月刊

1006-7191

ams@imr.ac.cn

024-83978879

110016

沈阳文化路72号

金属学报（英文版）/Journal Acta Metallurgica SinicaCSCDCSTPCD北大核心EISCI
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收录年代

    Multi-scale Study of the Formation and Evolution of M6C Carbides in High-Tungsten Superalloys

    Xiang FeiNaicheng ShengShijie SunShigang Fan...
    1995-2007页
    查看更多>>摘要：The formation and evolution of M6C carbides in high-W superalloy following solution treatment was investigated at different temperatures.Initially,during solid solution treatment,MC and M6C carbides was precipitated in the alloy.As the tempera-ture increased,the morphology of M6C carbides transitioned from granular to needle-like.During the solution treatment at 1255 ℃,the MC carbides degraded and transformed into M6C carbides,forming a symbiotic relationship between them.Nonetheless,no clear orientation relationship was observed between the two types of carbides.After further increasing the temperature to 1270 ℃,the precipitation of needle-like M6C carbides in the dendrite arm was confirmed.This was supported by electron probe X-ray micro-analyzer and selected area electron diffraction patterns.Subsequently,a detailed examination of the three-dimensional morphology and orientation relationship of the needle-like phase with the matrix was carried out using focused-ion-beam and transmission electron microscopy techniques.The results indicated that the flat interface of the needle phase exhibited a specific orientation relationship with the matrix.However,in the three-dimensional plane,the interfaces between the needle-like phase and the matrix were not straight.Furthermore,no clear orientation relationship between the non-straight interfaces and the matrix was observed.As the solution temperature increased,the tensile proper-ties at room temperature progressively decreased,while the stress rupture properties peaked at 1260 ℃,suggesting that the alloy demonstrated its optimal comprehensive performance at this temperature.A subsequent analysis was conducted on the longitudinal section of the fracture using electron backscattered diffraction.The results showed a noticeable concentration of stress at the interface between MC and M6C carbides,which ultimately led to crack initiation at this interface.In addition,as the solid solution temperature increased,the quantity of symbiotic phases also increased.This phenomenon led to the initiation of cracks at multiple locations,which then propagated and interconnected.As a consequence,the tensile properties and stress rupture life of the alloy progressively deteriorated.
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    Microstructure Selection in Ton Class Ingot of Al17Cr10Fe33Ni36Mo2Ti2 Eutectic High Entropy Alloy

    Xinbo ShiYunji QiuXiaoyu BaiYiming Chen...
    2008-2018页
    查看更多>>摘要：The eutectic high entropy alloys have attracted extensive attention and are considered one of the most promising new metal materials.The microstructures of large eutectic high entropy alloy ingot with excellent casting performance have been rarely reported.In this study,we have prepared a ton class eutectic high entropy alloy ingot via vacuum induction melting for the first time.The evolution of microstructure and macro-segregation from the edge region to the core of the ingot were also revealed.It was found that there was no significant macro-segregation in ton class eutectic high entropy alloy ingot,and chemical elements were distributed uniformly.The coupled growth of the primary phases and eutectic colonies were homogeneously distributed in the ingot,and there is no traditional columnar grain region from the edge region of the ingot to the core.The tensile strength of the sample in the R/2 region of the ton class ingot with elongation greater than 10％is 892.3 MPa,showing an excellent comprehensive mechanical property.This study exhibits an important guidance for the industrial application of large eutectic high entropy alloy casting ingot.
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    Microstructure,Mechanical and Wear Resistance Properties of AlCoCrFeNi2.1-xNi3Al Eutectic High-Entropy Alloy Matrix Composites

    Li LiXiao KongHui JiangWenna Jiao...
    2019-2028页
    查看更多>>摘要：AlCoCrFeNi2.1-xNi3Al(x=0,5.0,7.5,and 10 wt％,denoted as Ni3A10,Ni3A15.0,Ni3A17.5,and Ni3A110)eutectic high-entropy alloy(EHEA)matrix composites were fabricated by mechanical alloying and spark plasma sintering methods.The effects of Ni3Al content on the microstructures,mechanical and wear properties of AlCoCrFeNi2.1 EHEA were inves-tigated.The results indicate that the AlCoCrFeNi2.1-xNi3Al composites present cellular grid morphologies composing of FCC/L12 and B2 phases,and a small amount of Al2O3 and Cr7C3 phases.The addition of Ni3Al significantly enhanced the compressive yield strength,compressive fracture strength,compressive strain and wear properties of the AlCoCrFeNi2.1 composites.In particular,the Ni3Al10 composite exhibits excellent comprehensive mechanical properties.The compressive yield strength,compressive fracture strength and compressive strain of the Ni3Al10 composite,are 1845 MPa,2301 MPa and 10.1％,respectively.The friction coefficient,wear width and depth,and mass loss of the Ni3A110 composite were 0.40,0.9 mm,20.5 mm,0.016 g,respectively.Moreover,the wear mechanism of the Ni3Al10 composite is major abrasive wear with a small amount of adhesive wear.
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    Microstructure Evolution and High Strength-Ductility Synergy of Ti-13Nb-13Zr-2Ta Alloy Fabricated by Laser Powder Bed Fusion

    Libo ZhouBiao PengJian ChenYanjie Ren...
    2029-2044页
    查看更多>>摘要：This work systematically investigates the densification,microstructure evolution and the attainment of high strength-duc-tility in Ti-13Nb-13Zr-2Ta alloy processed by laser powder bed fusion(LPBF).A narrow and viable process window(Plaser power=175 W,vscanning speed=1000 mm/s,hscanning distance=0.1 mm and dlayer thickness=0.03 mm)was accordingly deter-mined and the relative density of Ti-13Nb-13Zr-2Ta alloy reaches 99.76％.The depth of molten pool increases gradually with the increase of energy density,and the relationship between the depth of molten pool and energy density has been quantitatively described.Three types of α'martensites with average grain width less than 3 μm can be observed in the LPBF-fabricated Ti-13Nb-13Zr-2Ta alloys,attributed to the significantly high cooling rate and remelting process.The fine grain size,high density dislocations,nanotwins,ordered oxygen complexes and α+α"heterostructure all contributed to the high strength(1037.75±25.18 MPa)and ductility(20.32％±1.39％)of LPBF-fabricated Ti-13Nb-13Zr-2Ta alloy in this work.
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    Improvement of Formation,Microstructure and Mechanical Properties of TIG Welded TC4 Titanium Alloy by Ultrasonic Coaxial Radiation

    Yihao GaoBoqiao RenYunhao ChenXinchen Sui...
    2045-2056页
    查看更多>>摘要：In this study,the effects of ultrasonic coaxial assisted TIG welding(U-TIG)on the formation,microstructure,and mechanical properties of TC4 titanium alloy welded joints were investigated.The results indicated that at optimal ultrasonic power and welding current settings,remarkable improvements of welded joint were observed.Specifically,the weld depth-to-width ratio increased by 267％compared to conventional TIG welding,reaching 0.22.Furthermore,the microhardness of the welded seam increased by 53％,reaching 550.1 HV,while the tensile strength of the welded joint rose to 1197.7 MPa,represent-ing a 12.2％enhancement.The compressing effect of ultrasound concentrates the energy of the arc,thereby improving the penetration depth of the welded seam.In addition,ultrasonic cavitation plays a crucial role in refining the grain structure of the weld seam,consequently enhancing its strength.
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    Interfacial Microstructure Evolution and Mechanical Properties of TC4/MgAl2O4 Joints Brazed with Ti-Zr-Cu-Ni Filler Metal

    Jiafen SongWei GuoShiming XuDing Hao...
    2057-2067页
    查看更多>>摘要：In the present study,Ti-Zr-Cu-Ni amorphous filler metal was used to braze MgAl2O4 ceramic and Ti-6A1-4V(TC4)at 875,900,925,950,975 and 1000 ℃ for 10 min.The effects of brazing temperature on interfacial microstructure and mechanical properties of the joints were analyzed.The results showed that typical microstructure of the TC4/MgAl2O4 joint was solid solution(SS)α-Ti,acicular α-Ti+(Ti,Zr)2(Ni,Cu)layer,metallic glasses and TiO.With the increase in brazing temperature,(Ti,Zr)2(Ni,Cu)layer gradually dispersed at bonding interface,a continuous layer of TiO appears near MgAl2O4 ceramic.With the increase in brazing temperature,the hard and brittle(Ti,Zr)2(Ni,Cu)layer gradually dispersed,resulting in the maximum shear strength of 39.5 MPa.The high-resolution TEM revealed the presence of amorphous structure,which is composed of Ti,Zr,Cu,Ni and Al.The values of δ and ΔHmix are calculated to be about 8％and-39.82 kJ/mol for the amorphous phase.
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    Design of Ultra-Strong As-Cast Titanium Alloy at 600 ℃ by Using Cluster Formula

    Zhihao ZhuCenyang WangTianyu LiuShuang Zhang...
    2068-2082页
    查看更多>>摘要：A Ti-5.4Al-6.4Zr-6.2Sn-0.4Mo-1.6W-0.4Nb-3.2Ta-0.5Si alloy is designed following cluster formula approach that achieves a strength level of 1 GPa at 600 ℃ in the as-cast state,superior to any existing high-temperature Ti alloys.Its com-position is formulated by 17 basic units,α-{[Al-Ti12](AlTi2)}12+β-{[Al-Ti12Zr2](Mo0.125Nb0.125Ta0.5W0.25Sn1.5Si0.5)}5,each unit covering a nearest-neighbor cluster plus a few next-neighbor glue atoms.This design is on the basis of the composition formula of Ti65 alloy,with an enhanced β stability via more Zr,Mo,Nb,Ta,W,Sn,and Si co-alloying.Upon copper-mold pour casting,this alloy shows a good microstructure stability.In tensile testing below at 650 ℃,its α plates thickness is nearly at the same level of 0.2 μm,which is much smaller than 0.7-0.8 μm of Ti65 at the same condition.The changes in volume fraction of β phase are increased by 86％,much less than by 105％in Ti65.Its room-temperature strength reaches the ultra-high-strength level,with an ultimate tensile strength of 1328 MPa and a yield strength of 1117 MPa,with a moderate elongation of 3.8％.At 600 ℃,its ultimate tensile strength of 1017 MPa and yield strength of 936 MPa are superior to those of any existing high-temperature Ti alloys,with an elongation of 7.2％.At 650 ℃,its ultimate tensile strength of 848 MPa still maintains a high level.
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    Achieving Twin Strengthening in Bulk Aluminum via Adding Nanoparticles Combined with Tailoring Hot Pressing Temperature

    Ke ZhaoZhongying DuanJinling LiuLinan An...
    2083-2093页
    查看更多>>摘要：It is extremely difficult to strengthen bulk aluminum(Al)by twins,due to its high stacking fault energy under standard loading conditions.In this study,a simple yet effective solution was proposed for introducing twins to strengthen bulk Al.The method involves the addition of nanoparticles with high volume fraction combined with the tailoring of sintering temperature toward the melting point of Al during hot pressing.Sintering temperature plays an important role in forming twins in bulk Al containing high content nanoparticles.The twin content increases with increasing sintering temperature in the range of 590-640 ℃.At sintering temperature of 640 ℃,the twin content reaches 17％,enabling the significant improvement in the yield strength of the bulk Al from 251 to 400 MPa,compared with the sample with few or no twins.The twin strengthening may serve as a major strengthening mechanism for bulk Al,and its strengthening contribution is comparable to the dominant Orowan strengthening resulting from the added nanoparticles.
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    Effect of Glass Tube Suction Casting on Solidification Process and Si Refinement of Hypereutectic Al-Si Alloy

    Chengcheng HanYuna WuHao HuangChen Chen...
    2094-2105页
    查看更多>>摘要：This study unpicks the influence of the glass tube suction casting(GTSC)with different inner diameters(8,10,12 and 14 mm)on the solidification process of the hypereutectic Al-Si alloy(A390)and dissects the underlying mechanisms of the Al-Si divorced eutectic and refinement degree of the primary silicon particles(PSPs).The results show that a smaller inner diameter of the glass tube is more favorable for achieving Al-Si divorced eutectic in GTSC A390 alloy.Conversely,a larger inner diameter is more conducive to the formation of the lamellar eutectic Si.The GTSC A390 alloy with an inner diameter of 10 mm achieves the smallest average equivalent diameter(approximately 7.4 μm)of the PSPs.Being the prior diffusion channels for solute atoms,the grain boundaries and twin growth grooves of PSPs attract solute atoms(Cu,Mg,etc.)to enrich.The enriched solute atoms occupy the diffusion destinations of some Si atoms,which limits the overall growth of PSPs.These findings provide new insights into developing a simple and effective manufacturing process to refine the primary and eutectic Si phases in hypereutectic Al-Si alloys.
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    Strengthening Mechanisms and Mechanical Characteristics of Heterogeneous CNT/Al Composites by Finite Element Simulation

    Hui FengShu YangShengyuan YangLi Zhou...
    2106-2120页
    查看更多>>摘要：The refined explicit finite element scheme considering various strengthening mechanisms and damage modes is proposed for simulation of deformation processes and mechanical properties of carbon nanotube(CNT)-reinforced bimodal-grained aluminum matrix nanocomposites.Firstly,the detailed microstructure model is established by constructing the geometry models of CNTs and grain boundaries,which automatically incorporates grain refinement strengthening and load transfer effect.Secondly,a finite element formulation based on the conventional theory of mechanical-based strain gradient plasticity is developed.Furthermore,the deformation and fracture modes for the nanocomposites with various contents and distribu-tions of coarse grains(CGs)are explored based on the scheme.The results indicate that ductility of the composites first increases and then decreases as the content of CGs rises.Moreover,the dispersed distribution exhibits better ductility than concentrated one.Additionally,grain boundaries proved to be the weakest component within the micromodel.A series of interesting phenomena have been observed and discussed upon the refined simulation scheme.This work contributes to the design and further development of CNT/Al nanocomposites,and the proposed scheme can be extended to various bimodal metal composites.
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