ABSTRACT

Al _x CoCrCuFeNi high entropy alloys were synthesised through mechanical alloying and spark plasma sintering. Different alloys were produced by varying the aluminium content (x = 0.5, 1.5, 2.5 and 4). The influence of the milling duration on the evolution of microstructure, constituent phases and morphology was studied. Milling time increasing resulted in grain refinement and higher solid solution homogenisation characterised by a high internal strain. As a consequence of aluminium addition, the materials’ microstructure evolved from FCC and BCC phases to FCC, BCC and ordered BCC phases. Both mechanical alloying and SPS conditions as well as aluminium content let to grain refinement and mechanical properties variations. In particular, hardness increased with increasing the aluminium content. The aluminium percentage and the consequent phases evolution is responsible for the microstructural stability at high temperatures.

摘要

通过机械合金化和火花等离子体烧结合成了Al _x CoCrCuFeNi高熵合金。通过改变铝含量（x  = 0.5、1.5、2.5和4）。研究了铣削时间对显微组织，组成相和形态演变的影响。研磨时间的增加导致晶粒细化和较高的固溶均质化，其特征在于高内部应变。由于添加铝，材料的微观结构从FCC和BCC相演变为FCC，BCC和有序BCC相。机械合金化和SPS条件以及铝含量都可以改善晶粒细化和机械性能。特别地，硬度随着铝含量的增加而增加。铝百分比和随后的相演变是高温下显微组织稳定性的原因。