Ultra-fine grain TixVNbMoTa refractory high-entropy alloys with superior mechanical properties fabricated by powder metallurgy
Ultra-fine grain TixVNbMoTa refractory high-entropy alloys with superior mechanical properties fabricated by powder metallurgy
复制标题
粉末冶金制备具有优异机械性能的超细晶粒 TixVNbMoTa 难熔高熵合金
DOI：
10.1016/j.jallcom.2020.158592
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发表时间：
2021-02-03
影响因子：
6.2
通讯作者：
Yang, Jianlei
中科院分区：
文献类型：
--
作者：
Liu, Qing;Wang, Guofeng;Yang, Jianlei
TixVNbMoTa 难熔高熵合金 (RHEA) 是在经典 VNbMoTaW RHEA 的基础上通过机械合金化 (MA) 和放电等离子烧结 (SPS) 制造而成。系统研究了 Ti 含量对 TixVNbMoTa RHEA 显微组织和力学性能的影响。结果表明，Ti含量较高的球磨粉在MA过程初期团聚严重，导致机械合金化时间延长。 MA 工艺后，所有组中的机械合金化粉末均表现出单一体心立方 (BCC) 相。烧结合金由超细基体和析出相组成。随着Ti含量的增加，基体相和析出相的晶粒尺寸以及析出相的体积分数均增大。 MA和SPS工艺以及Ti的替代不仅大大降低了合金的密度，而且显着提高了合金的延展性、强度和比强度。随着TixVNbMoTa RHEA中Ti含量的增加，屈服强度先降低后升高，这主要是由于晶界强化作用减弱，而替代固溶强化和间隙固溶强化作用增强。 Ti1.5和Ti2中析出相的尺寸和体积分数迅速增加，破坏了基体的连续性和变形的协调性，导致塑性下降。 (C) 2021 Elsevier B.V. 保留所有权利。
TixVNbMoTa refractory high-entropy alloys (RHEAs) were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS) based on classic VNbMoTaW RHEA. The effect of Ti content on the microstructures and mechanical properties of the TixVNbMoTa RHEAs were systematically investigated. The results showed that the milling powders with more Ti content were agglomerated severely in the early stage of the MA process, leading to the extension of mechanical alloying time. The mechanically alloyed powders in all groups exhibited single body-centered-cubic (BCC) phase after the MA process. The sintered alloys were consisted of ultra-fine matrix and precipitation phase. The grain sizes of the matrix and precipitation phases, as well as the volume fraction of the precipitation phases were increased with the increase of Ti content. The MA and SPS processes and the replacement of Ti not only greatly reduce the densities, but also significantly improved the ductility, strength and specific strength of the alloys. The yield strengths were decreased first and then increased with the increase of Ti content in the TixVNbMoTa RHEAs, which is mainly attributed to the weakened effect of grain boundary strengthening, and the enhanced effect of the substitution solid solution strengthening and the interstitial solid solution strengthening. The rapidly increased sizes and volume fractions of the precipitated phases in Ti1.5 and Ti2 destroyed the continuity of matrix and the coordination of deformation, resulting in the decrease of ductility. (C) 2021 Elsevier B.V. All rights reserved.