Effect of Ti Content on Microstructure and Mechanical Properties of the Co39.2Ni39.2Al21.6-xTixDual-phase High Entropy Alloys
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摘要: 本研究设计并制备了成分为Co39.2Ni39.2Al21.6-xTix(x=2、4和6)的双相高熵合金。三种合金均为FCC-B2双相结构,FCC相中存在弥散的纳米级L12有序析出相,B2相中存在板条状L10马氏体相。随着Ti含量的增加,FCC相的体积分数、L12相的体积分数和尺寸均增大,B2相的体积分数减小。三种合金中,Co39.2Ni39.2-Al15.6Ti6合金具有最优的强塑性匹配,这来源于变形过程中B2相中应力诱发的马氏体相变和FCC相中L12有序析出相提供的高加工硬化率。本研究为通过合金化调控双相高熵合金组织,优化其综合力学性能提供了理论参考依据。Abstract: Three dual phase high entropy alloys with a composition of Co39.2Ni39.2Al21.6-xTix(x=2, 4, and 6) are prepared in this work. All the three alloys display an FCC-B2 dual phase structure. Dispersed nanoscale L12 ordered precipitate phases are presented in FCC, and lath-like L10 martensite presented in B2 phase. With the increase of Ti content, the volume fractions of FCC and L12 phases and size of L12 phase increase, and the volume fraction of B2 phase decreases. The Co39.2Ni39.2Al15.6Ti6 alloy shows the most excellent combination of strength and ductility. The high strength and plasticity come from the stress induced martensitic transformation in the B2 phase during the deformation process, and the high work hardening rate provided by the L12 ordered precipitate phase in the FCC phase. This work provides a theoretical reference for designing the microstructure of the dual phase high entropy alloys through alloying to enhance their comprehensive mechanical properties.
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