Bönisch M, Wu Y, Sehitoglu H
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206W. Green St., Urbana, IL, 61801, USA.
Sci Rep. 2018 Jul 13;8(1):10663. doi: 10.1038/s41598-018-28784-1.
A face-centered-cubic (fcc) oriented FeCoCrNiAl dual-phase high entropy alloy (HEA) was plastically strained in uniaxial compression at 77K and 293K and the underlying deformation mechanisms were studied. The undeformed microstructure consists of a body-centered-cubic (bcc)/B2 interdendritic network and precipitates embedded in 〈001〉-oriented fcc dendrites. In contrast to other dual-phase HEAs, at both deformation temperatures a steep rise in the stress-strain curves occurs above 23% total axial strain. As a result, the hardening rate associated saturates at the unusual high value of ~6 GPa. Analysis of the strain partitioning between fcc and bcc/B2 by digital image correlation shows that the fcc component carries the larger part of the plastic strain. Further, electron backscatter diffraction and transmission electron microscopy evidence ample fcc deformation twinning both at 77K and 293K, while slip activity only is found in the bcc/B2. These results may guide future advancements in the design of novel alloys with superior toughening characteristics.
一种面心立方（fcc）取向的FeCoCrNiAl双相高熵合金（HEA）在77K和293K下进行单轴压缩塑性应变，并研究了其潜在的变形机制。未变形的微观结构由体心立方（bcc）/B2枝晶间网络和嵌入〈001〉取向fcc枝晶中的析出物组成。与其他双相高熵合金不同，在两个变形温度下，应力-应变曲线在总轴向应变超过23%时都会急剧上升。结果，相关的硬化率在约6 GPa的异常高值处饱和。通过数字图像相关分析fcc和bcc/B2之间的应变分配表明，fcc组分承担了大部分塑性应变。此外，电子背散射衍射和透射电子显微镜证据表明，在77K和293K时fcc都有大量变形孪晶，而在bcc/B2中仅发现滑移活动。这些结果可能会指导具有优异增韧特性的新型合金设计的未来进展。
