Al_(0.1)CoCrFeNi高熵合金在准静态扭转下的微观组织和力学性能

Microstructure and Mechanical Properties of Al_(0.1)CoCrFeNi High-entropy Alloy under Quasi-static Torsion

将Al_(0.1)CoCrFeNi高熵合金进行准静态扭转加载,利用X射线衍射分析仪、扫描电镜、电子背散射衍射、纳米压痕以及准静态拉伸实验,研究了扭转后试样的梯度微结构和力学性能。除了晶粒细化,高熵合金的梯度微结构还包括位错及孪晶亚结构的梯度分布,即含量从中心到边缘不断增加。准静态拉伸实验表明,由于梯度微结构和较高的加工硬化能力,扭转后的拉伸板可显著提高拉伸强度,同时保持良好的塑性。因此,梯度应变、额外的加工硬化能力和背应力效应实现了强度和塑性的协调变形。此外,纳米压痕硬度沿径向不断增加,同样呈现明显的梯度分布,其强化机制主要归因于细晶强化和加工硬化。

Al_(0.1)CoCrFeNi high-entropy alloy bar was subjected to quasi-static torsion.Using XRD,SEM,EBSD,nanoindentation and quasi-static tensile experiment,the gradient microstructure and mechanical properties of the sample after torsion were systematically investigated.In addition to grain refinement,the gradient microstructure also includes dislocations and twin substructures whose contents increase from center to edge.The tensile test shows that the tensile plate after torsion can significantly improve tensile strength while remaining good ductility due to gradient microstructure and the higher work-hardening ability.Therefore,the gradient strain,additional work-hardening ability and back stress effect lead to an excellent combination of strength and plasticity.In addition,the nanohardness continues to increase along the radial direction,i.e.,an obvious gradient distribution,which is mainly attributed to grain-boundary strengthening and work-hardening effect.