To elucidate deformation behavior behind the exceptional mechanical properties of CrCoNi based medium entropy alloys, the deformation related microstructural parameters were determined by using in situ neutron diffraction and peaks profile analysis methods. Superior tensile strength and elongation of the CrCoNi alloy is relevant to higher twin fault probability (P_tw, up to 3.8%) and dislocation density (ρ, up to 9.7 x 10¹⁵ m⁻²) compared to those (1.3% and 3.4 x 10¹⁵ m⁻², respectively) of the CrCoNiFe at 293K. Meanwhile, at 140K, the P_tw of the CrCoNiFe significantly increased up to 4.4% with the stable ρ of ∼5.0 x 10¹⁵ m⁻² and its mechanical properties overwhelm those of the CrCoNi at 273K. Such twinning dominant deformation mechanism at low temperature is also assured by lower stacking fault energy (SFE) of the CrCoNiFe (7.4 mJ/m²) at 140K compared to those of the CrCoNi (16.1 mJ/m²) and CrCoNiFe (32.1 mJ/m²) alloys at 293K.

为了阐明CrCoNi基中等熵合金优异力学性能背后的变形行为，使用原位中子衍射和峰轮廓分析方法确定了变形相关的微结构参数。CrCoNi合金优异的抗拉强度和伸长率与更高的孪晶断裂概率（P _tw，最高3.8％）和位错密度（ρ，最高9.7 x 10 ¹⁵  m ^-2）有关（与之相比，分别为1.3％和3.4 x 293K时的CrCoNiFe分别为10 ¹⁵  m ^-2。同时，在140K时，CrCoNiFe的P _tw显着提高至4.4％，而ρ保持稳定。约为5.0 x 10 ¹⁵  m ^-2，其机械性能超过了273K时CrCoNi的机械性能。与CrCoNi（16.1 mJ / m ²）和CrCoNiFe（32.1 mJ / m ）相比，在140K时CrCoNiFe（7.4 mJ / m ²）的堆垛层错能（SFE）也较低，从而确保了这种在低温下的孪生主导变形机制。293K的m ²）合金。