Tsianikas Simon, Chen Yujie, Jeong Jiwon, Zhang Siyuan, Xie Zonghan
School of Mechanical Engineering, The University of Adelaide, SA 5005, Australia.
Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf, Germany.
Nanoscale. 2021 Feb 18;13(6):3602-3612. doi: 10.1039/d0nr06798a.
Multiple interstitial elements (B, C and O), were incorporated into a body-centred cubic (BCC) FeMnCoCr-based interstitial high entropy alloy (iHEA). While achieving an impressive yield strength of 2.55 GPa, the new alloy also possesses appreciable ductility under mechanical loading. The unusual combination of hardening effects brought about by interstitial atoms, compositional fluctuations, and fine grain size greatly strengthened the alloy by inhibiting dislocation motion. Moreover, interstitial elements helped reinforce the grain boundaries through segregation and also assisted in tuning the phase stability. The new alloy transformed from the BCC to hexagonal closed-packed (HCP) phase initially. With increasing load the HCP phase was gradually converted into face-centred cubic (FCC); the resultant HCP/FCC nanolaminates enhanced plasticity via strain partitioning. Under higher loads, the FCC phase became dominant, giving rise to deformation twinning. Taken together, the newly developed BCC structured iHEA affords not only high strength, but also confers remarkable ductility through multiple deformation pathways.
多种间隙元素（硼、碳和氧）被引入到一种体心立方（BCC）结构的FeMnCoCr基间隙高熵合金（iHEA）中。这种新型合金在实现2.55 GPa的令人印象深刻的屈服强度的同时，在机械加载下也具有可观的延展性。间隙原子、成分波动和细晶粒尺寸所带来的硬化效应的异常组合，通过抑制位错运动极大地强化了合金。此外，间隙元素通过偏析有助于强化晶界，还协助调整相稳定性。新型合金最初从BCC相转变为六方密排（HCP）相。随着载荷增加，HCP相逐渐转变为面心立方（FCC）相；由此产生的HCP/FCC纳米层通过应变分配提高了塑性。在更高载荷下，FCC相占主导地位，引发变形孪晶。综上所述，新开发的BCC结构iHEA不仅提供高强度，还通过多种变形途径赋予显著的延展性。
