Unique deformation behavior and microstructure evolution in high-temperature processing of a low-density TiAlVNb2 refractory high-entropy alloy
Unique deformation behavior and microstructure evolution in high-temperature processing of a low-density TiAlVNb2 refractory high-entropy alloy
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DOI：
10.1016/j.jallcom.2021.160962
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发表时间：
2021-07-01
影响因子：
6.2
通讯作者：
Liu, X. W.
中科院分区：
文献类型：
--
作者：
Bai, Z. C.;Ding, X. F.;Liu, X. W.
研究了一种新型轻质耐火高熵合金（RHEA） TiAlVNb2的热变形行为和显微组织演变。在10(-3)s(-1) ~ 10(-1) s（-1）的应变速率和1000 ~ 1200℃的温度下进行单轴压缩，应力-应变曲线结合电子反散射衍射分析表明，热压缩过程中发生了加工硬化、动态再结晶（DRX）和动态恢复（DRV）。采用arrhenius型幂律关系进行流变应力分析，表观活化能在401 ~ 375kj之间。Mol（-1）除以整个应变范围。DRX是主要的软化机制之一，随着温度的升高或应变速率的降低，DRX晶粒的尺寸和分数呈典型的增大趋势。然而，进一步的分析揭示了一个独特的DRX特征，即在该RHEA中发生了不连续和连续的DRX过程。通过原始晶界的膨出（迁移）、籽粒平均取向图和透射电镜验证了非连续DRX；而累积取向错误（指向原点）和在原晶粒内部形成的新晶粒则支持连续DRX的存在。(C) 2021 Elsevier B.V.版权所有
Thermal deformation behaviors and microstructure evolution of a novel light refractory high-entropy alloy (RHEA) TiAlVNb2 were investigated in detail. Uniaxial compression was implemented at different strain rates from 10(-3) s(-1) to 10(-1) s(-1) and various temperatures from 1000 degrees C to 1200 degrees C. Stress-strain curves combined with electron back scattered diffraction analysis indicate that work hardening, dynamic re-crystallization (DRX) and dynamic recovery (DRV) occur during the thermal compression. Flow stress analysis carried out by the Arrhenius-type power law relationship suggests a high apparent activation energy of 401-375kJ.mol(-1) over the whole range of strain. The DRX acts as one of the main softening mechanisms, in which the DRX grains show a typical trend of increased size and fraction with increased temperature or/and decreased strain rate. Further analyses, however, reveal a unique DRX feature that both discontinuous and continuous DRX processes take place in this RHEA. The discontinuous DRX was proved by bulge (migration) of original grain boundaries, kernel average misorientation map and transmission electron microscopy; while the cumulative misorientation (point to origin) and the new grains formed at original grain interior support the existence of continuous DRX (CDRX). (C) 2021 Elsevier B.V. All rights reserved.