无延展性损失下低密度脉冲电流诱导细化次生α相强化Ti-6Al-4V-0.5Mo-0.5Zr合金

Low-Density Pulsed Current Induced Refinement of Secondary α Phase for Strengthening Ti-6Al-4V-0.5Mo-0.5Zr Alloy Without Sacrificing Ductility

摘要:

对不同固溶处理的Ti-6Al-4V-0.5Mo-0.5Zr合金进行了低密度短时脉冲电流辅助时效处理。结果表明，脉冲电流辅助时效过程中，大量的α_p相回熔转变为新的β相，然后新β相主要转变为β_t组织或偶尔转变为新的α_p相，导致晶粒显著细化，尤其是层片状α_s相。与常规时效相比，脉冲电流辅助时效过程在保持相同延展性的同时显著提高了强度，实现了屈服强度932 MPa、抗拉伸强度1042 MPa和延伸率12.2%的优异组合。这主要归因于β_t组织含量的增加、明显的晶粒细化效应以及β_t区域内多个变体α_s集束的滑移阻碍作用。

Abstract:

Low-density short-duration pulsed current-assisted aging treatment was applied to the Ti-6Al-4V-0.5Mo-0.5Zr alloy subjected to different solution treatments. The results show that numerous α_p phases redissolve into the new β phase during the pulsed current-assisted aging process, and then the newly formed β phase is mainly transformed into the β_t phase, with occasional transition to new α_p phase, leading to a remarkable grain refinement, especially for the lamellar α_s phases. In comparison to conventional aging treatment, the pulsed current-assisted aging approach achieves a significant enhancement in strength without degrading ductility, yielding an excellent mechanical property combination: a yield strength of 932 MPa, a tensile strength of 1042 MPa, and an elongation of 12.2%. It is primarily ascribed to the increased fraction of β_t phases, the obvious grain refinement effect, and the slip block effect induced by the multiple-variant α_s colonies distributed within β_t phases.