摘要
难熔高熵合金(refractory high entropy alloys,RHEAs)因具备高的服役温度和优异的热稳定性在航空航天等超高温领域有广阔的应用前景。然而,难熔高熵合金目前面临综合力学性能不足等问题,限制了其进一步应用。针对此,本文在WMoTaV基础上进一步引入Ti元素,制备一种WMoTaVTi难熔高熵合金,重点研究烧结温度对合金烧结致密化、显微组织和力学性能的影响。研究结果表明:随着烧结温度的升高,合金的晶粒尺寸逐渐增加,屈服强度呈现先增加后降低的趋势。当烧结温度为1500℃时,合金具有最佳的综合性能,此时其相对密度超过99%,室温压缩屈服强度为1672 MPa,断裂应变为16.6%,断口形貌主要为沿晶断裂;相比于WMoTaV难熔高熵合金,合金的屈服强度提高了18%。由于粉末冶金过程中引入少量O元素,该合金主要由BCC基体相和少量FCC结构的TiO析出相组成,随着烧结温度的升高,基体的固溶度增加,TiO相的体积分数逐渐减少。合金强度的提高主要归因于固溶强化和析出强化两种强化机制。
Refractory high entropy alloys(RHEAs)have broad application prospect in ultra-high temperature filed such as aerospace because of its high service temperature and excellent thermal stability.However,RHEAs are facing the problems of insufficient comprehensive mechanical properties and further application is limited.In order to solve these problems,a kind of WMoTaVTi RHEA was prepared by introducing Ti element on the basis of WMoTaV RHEA,and the effect of sintering temperature on sintering densification,microstructure and mechanical properties of WMoTaVTi RHEAs were systematically investigated.The results show that the grain size of the alloy increases gradually and the yield strength of the alloy increases first and then decreases with the increase of sintering temperature.When the sintering temperature is 1500℃,the alloy exhibits the optimal comprehensive properties at room temperature and its relative density exceeds 99%,with compressive yield strength of 1672 MPa and a fracture strain of 16.6%,and the fracture morphology is mainly intergranular fracture.Compared with WMoTaV RHEA,the yield strength of WMoTaVTi RHEA increases by 18%.Through the multi-dimensional analysis,due to the introduction of a small amount of O into the powder metallurgy process,the alloy mainly consists of BCC matrix phase and a small amount of TiO precipitation phase with FCC structure.With the increase of sintering temperature,the solid solubility of the matrix increases,and the volume fraction of TiO phase decreases gradually.The improvement of strength can be attributed to the solid solution strengthening and precipitation strengthening.
作者
杨一涵
韩勇
唐思思
李媛
袁媛
姜雪
刘瑛
YANG Yihan;HAN Yong;TANG Sisi;LI Yuan;YUAN Yuan;JIANG Xue;LIU Ying(State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China;Zijin Mining Renewable Energy and Advanced Materials(Changsha)Co.Ltd.,Changsha 410036,China)
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2024年第8期2940-2950,共11页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(52371041)。
关键词
难熔高熵合金
放电等离子烧结
显微组织
力学性能
refractory high entropy alloys(RHEAs)
spark plasma sintering(SPS)
microstructure
mechanical properties
