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.

中文翻译：

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AlxCoCrCuFeNi HEAs机械合金化和放电等离子烧结的晶体结构演变

摘要 通过机械合金化和放电等离子烧结合成了 Al x CoCrCuFeNi 高熵合金。通过改变铝含量（x = 0.5、1.5、2.5 和 4）生产不同的合金。研究了球磨时间对微观结构、组成相和形貌演变的影响。研磨时间的增加导致晶粒细化和以高内部应变为特征的更高的固溶体均匀化。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 条件以及铝含量都会导致晶粒细化和机械性能发生变化。特别是硬度随着铝含量的增加而增加。