Achieving ultra-high strength and ductility in equiatomic CrCoNi with partially recrystallized microstructures
Achieving ultra-high strength and ductility in equiatomic CrCoNi with partially recrystallized microstructures
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DOI：
10.1016/j.actamat.2018.12.015
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发表时间：
2019-02-15
期刊：
影响因子：
9.4
通讯作者：
Mills, M. J.
中科院分区：
文献类型：
--
作者：
Slone, C. E.;Miao, J.;Mills, M. J.
尽管许多单相中等和高熵合金具有优异的机械性能，但其屈服强度有限。虽然晶粒细化为进一步强化提供了一个机会，但它需要对延性做出重大且不受欢迎的妥协。因此，这项工作探索了一种替代的、简单的加工路线，通过冷轧和退火等原子CrCoNi合金来获得强度，以产生不均匀的、部分再结晶的微观组织。拉伸试验表明，我们的方法显著提高了单相CrCoNi合金的屈服强度(接近1100 Mpa)，同时保持了良好的塑性(总延伸率类似于23%)。扫描和透射电子显微镜表明，强化是由于未再结晶的晶粒保留了形变诱发的孪晶和很高的位错密度。还利用加载-卸载-再加载试验和晶粒度数字图像相关方法研究了塑性变形在高非均质微结构中的累积。(C)2018 Acta Materialia Inc.由Elsevier Ltd.出版。保留所有权利。
Despite having otherwise outstanding mechanical properties, many single-phase medium and high entropy alloys are limited by modest yield strengths. Although grain refinement offers one opportunity for additional strengthening, it requires significant and undesirable compromises to ductility. This work therefore explores an alternative, simple processing route to achieve strength by cold-rolling and annealing an equiatomic CrCoNi alloy to produce heterogeneous, partially recrystallized microstructures. Tensile tests reveal that our approach dramatically increases the yield strength (to similar to 1100 MPa) while retaining good ductility (total elongation similar to 23%) in the single-phase CrCoNi alloy. Scanning and transmission electron microscopy indicate that the strengthening is due to the non-recrystallized grains retaining their deformation-induced twins and very high dislocation densities. Load-unload-reload tests and grain-scale digital image correlation are also used to study the accumulation of plastic deformation in our highly heterogeneous microstructures. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.