The tension-compression asymmetry of martensite phase transformation in a metastable Fe40Co20Cr20Mn10Ni10 high-entropy alloy
The tension-compression asymmetry of martensite phase transformation in a metastable Fe40Co20Cr20Mn10Ni10 high-entropy alloy
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DOI：
10.1007/s40843-020-1319-3
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
Xing-long An;Zhangwei Wang;S. Ni;M. Song
中科院分区：
文献类型：
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作者：
Xing-long An;Zhangwei Wang;S. Ni;M. Song
系统研究了亚稳面心立方（FCC）Fe40Co20Cr20Mn10Ni10高熵合金（HEA）在拉伸和压缩条件下的组织演变。结果表明，在压缩比拉伸下，更高的水平从FCC结构的马氏体相变到六方密排（HCP）结构，表明明显的拉压不对称性。压缩测试经历了更高的真应力，这进一步提供了更强的驱动力，以触发相变比那些在拉伸测试。除了马氏体相变外，在拉伸和压缩过程中位错平面滑移均占优势，沿着出现机械孪晶。在整个拉伸变形过程中，位错滑移起主导作用，而在压缩变形过程中，位错运动和马氏体相变都起关键作用。马氏体相变优选在晶粒或亚晶粒边界处成核，这是由于中等的堆垛层错能（SFE）为1.20 mJ m− 2。通过小角度晶界的部分位错发射形成HCP相为马氏体相变提供了额外的途径。因此，我们的研究非常有利于理解亚稳态HEAs的变形机制。© 2020，中国科学出版社和施普林格出版社德国，施普林格自然的一部分。
The microstructural evolution of a metastable face centered cubic (FCC) Fe40Co20Cr20Mn10Ni10 high-entropy alloy (HEA) under both tension and compression is systemically investigated. The results show much higher level of martensite phase transformation from FCC structure to hexagonal closed packed (HCP) structure under compression than tension, indicating a distinct tension-compression asymmetry. The compressive tests underwent higher true stresses, which further provided stronger driving forces to trigger the phase transformation than those in tensile tests. Except for the martensite phase transformation, dislocation planar slip prevails in both tension and compression, along with the occasional formation of mechanical twins. Dislocation slip dominates the whole tensile deformation, while both dislocation motions and martensite phase transformation play critical roles in the compressive deformation. The martensite phase transformation is preferred to nucleate at grain or subgrain boundaries due to a medium stacking fault energy (SFE) of∼ 20 mJ m− 2. The formation of HCP phase via partial dislocation emission from low angle grain boundaries offers additional pathways for martensite phase transformation. Our study thus remarkably benefits the understanding of the de formation mechanisms of metastable HEAs.© 2020, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.