Unexpected effects on creep resistance of an extruded Mg-Bi alloy by Zn and Ca co-addition:Experimental studies and first-principles calculations  被引量:1

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作  者:Zhenyu Xiao Shiwei Xu Weiying Huang Haifeng Liu Xuyue Yang Haikun Xu Chao Ma Chen Jin Zhanhong Lin 

机构地区:[1]College of Materials Science and Engineering,Hunan University,Changsha 410082,China [2]State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle,Hunan University,Changsha 410082,China [3]Suzhou Research Institute of Hunan University,Suzhou 215131,China [4]College of Mechanical and Vehicle Engineering,Hunan University,Changsha 410082,China [5]Hunan Jinfeng Machinery Technology Co.Ltd.,Loudi 417000,China [6]Key Laboratory of Efficient&Clean Energy Utilization,School of Energy and Power Engineering,Changsha University of Science&Technology,Changsha 410114,China [7]College of Materials Science and Engineering,Central South University,Changsha 410083,China [8]Information and Network Center,Central South University,Changsha 410083,China [9]Qinghai Salt Lake Teli Magnesium Co.Ltd.,Xining 810000,China

出  处:《Journal of Materials Science & Technology》2024年第34期166-186,共21页材料科学技术(英文版)

基  金:supported by the National Key R&D Program of China(No.2021YFB3701100);the Joint Funds of the National Natural Science Foundation of China(No.U22A20187);the Science and Technology Innovation Program of Hunan Province(Nos.2023RC3268,2021JC0005 and 2020RC4013);the Science Fund of State Key Laboratory of Advanced Design and Manu-facturing Technology for Vehicle(No.32117009);the Projects“Development of lightweight high-performance Mg alloys profiles manufacturing technologies”and“Research and development of room-temperature bendable Mg alloy thin sheets manufactur-ing technology”from QingHai Salt Lake Industry Co.,Ltd.(Nos.2022-Z-0810000000-21-ZC0609-0001 and 2022-Z-08);the“Technology Innovation 2025”Major Special Project of Ningbo City;The first-principles calculations work was carried out using software provided by the High Performance Computing Center of Central South University.

摘  要:In the present work,a new Mg-Bi based alloy is developed by the addition of Zn and Ca in equiva-lent atom fraction with Bi.Mg-Bi and Mg-Bi-Zn-Ca alloys were prepared by extrusion at a ram speed of 20 mm/s.Room temperature mechanical properties and creep behaviors at 423 K were investigated.The results show that Zn and Ca co-addition shows little influence on average grain size and texture in-tensity but changes the dispersive Mg_(3)Bi_(2)into Mg_(2)Bi_(2)Ca particles in different sizes and a lower density.Twinning is largely activated during room-temperature deformation.Consequently,a slightly decreased proof strength but tripled elongation is shown at room temperature.Unexpectedly,large enhancement in creep resistance is detected after the co-alloying of Zn and Ca and the minimum creep rate is reduced by 10 to 20 times in the BZX621 alloy.Stress exponent n=4-5 indicates that the creep is a dislocation-climb controlled type.Post-mortem characterization on microstructure shows slip of dislocationc+aare also largely found in B6 as well as BZX621 alloy and cross-slip is detected more severe in B6 alloy.Dynamic segregation and precipitation are also seen in both alloys.Bi-clusters are seen dispersive across the grains in B6 and so did the PFZs that could undermine creep resistance at the grain boundaries.By contrast,Zn-rich needle-like precipitates are developed at most“ends”ofc+adislocations,which would hinder the further dislocation motions and thus improve the creep resistance.First-principles cal-culations were adopted and the results show that the thermal stability and thermomechanical properties of Mg_(2)Bi_(2)Ca are much better than that of Mg_(3)Bi_(2).Stacking faults energy is lowered down with the co-addition of Ca and Zn,which could inhibit the rate of dislocation climb and cross-slip.As a result,the im-proved creep resistance is obtained in the Mg-Bi-Zn-Ca alloys.Microstructural and controlling mechanism changes by thermal activation result in the unexpected enhancement in creep resistance with decrea

关 键 词:Creep resistance First-principles calculations Mg-Bi alloy Microstructure SFE 

分 类 号:TG1[金属学及工艺—金属学]

 

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