Ti添加对U-5.7Nb-xTi合金相结构和力学性能的影响  

Effects of Ti Addition on Phase Structure and Mechanical Properties of U-5.7Nb-xTi Alloys

作　　者：吴敏[1] 张雷[1] 施韬 莫文林 张培[1] 张鹏国[1] 邹东利[1] 法涛[1] Wu Min;Zhang Lei;Shi Tao;Mo Wenlin;Zhang Pei;Zhang Pengguo;Zou Dongli;Fa Tao(Institute of Materials,China Academy of Engineering Physics,Mianyang 621900,China)

机构地区：[1]中国工程物理研究院材料研究所,四川绵阳621900

出　　处：《稀有金属材料与工程》2022年第9期3403-3408,共6页Rare Metal Materials and Engineering

基　　金：国家重点研发计划(2016YFB0700403);国家自然科学基金(51701191)。

摘　　要：采用电弧熔炼制备了不同Ti含量的U-5.7Nb-x Ti系列合金样品,并对其相组织结构和力学性能的演化规律进行了研究。结果表明,随着Ti含量的增加,淬火态U-5.7Nb-x Ti(x=0,0.6,1.2,1.8,质量分数,%)合金内首先会在α″相中形成γ0相,随后完全转化为γ0相,当Ti含量进一步上升至1.8%时整个材料表现出高温奥氏体的体心立方相。将Ti等原子换算为平衡铌浓度Nbeq后,各相成分的边界与U-Nb合金十分吻合。与此同时,U-5.7Nb-x Ti合金的硬度随着总合金含量的增加其硬度先降低后升高。通过分析U合金马氏体相变机制及金属材料固溶强化理论,发现U合金的相结构和力学行为分别由高温母相的屈服强度和马氏体相的孪晶能所决定。由于Ti和Nb的原子半径和体模量等物理参量非常相近,导致两者在对母相的固溶强化和对马氏体相孪晶能的贡献相当,进而使得Ti可以等原子替换Nb而对相结构和力学性能的影响较小。根据相同的物理机制,U-Nb-X三元合金(或更多元合金)可通过分析合金元素X的原子半径和体模量等物理参量,较为准确地预测不同X元素添加量对相结构和力学性能的影响,这为U-5.7Nb合金的进一步强化设计提供了理论依据和指导。U-5.7Nb-x Ti(wt%) alloys with different Ti contents were fabricated by arc-melting,and the evolution of phase structure and mechanical properties were studied.The results show that with the increase of Ti content,γ0 phase is first to appear in the α″ phase matrix,followed by its propagation.After completely transforming to γ0 phase in U-5.7Nb-1.2Ti,additional Ti alloying leads to the formation of the equilibrium γ12 phase.When the Ti content is increased to 1.8wt%,the whole material exhibits the body-centered cubic phase of austenite at high temperature.After the Ti atom is equivalently converted to the equilibrium niobium concentration Nb eq,the boundary of each phase composition is very consistent with the U-Nb alloy.Meanwhile,the hardness of U-5.7Nb-x Ti alloys is similar with those of U-Nb alloys with same total atomic contents.By analyzing the mechanism of transformation of the U-alloy and the theory of solid solution strengthening of the metal materials,the phase structure and mechanical behavior are considered to be closely related to the yield strength of the parent phase and twinning energies,respectively.Due to their similar physical parameters including atomic radii and bulk modulus,the solution strengthening effects of the parent phase and variation of the twinning energies led by Ti or Nb alloying are similar,which are responsible for the similarities of the phase structure and the mechanic al properties in U-Nb-Ti and U-Nb alloys.According to the same physical mechanism,the phase structure and the mechanical properties of U-Nb-X ternary alloys(or multi-element alloys) can be more accurately predicted by analyzing physical parameters such as the atomic radius and bulk modulus of alloying element X.These results and analyses provide theoretical basis and guidance for further strengthening design of U-5.7Nb alloy.

关 键 词：铀铌钛合金 相结构 力学性能 

分 类 号：TG146.8[一般工业技术—材料科学与工程]