Al_xCoCuFeNi高熵合金的组织结构与力学性能

Microstructure and Mechanical Properties of Al_xCoCuFeNi High Entropy Alloys

设计并制备了AlxCoCuFeNi系列高熵合金,系统研究了合金的组织结构及力学性能。结果表明,当x<0.85时,合金为单一的FCC晶体结构;随Al含量的增加,合金的晶体结构转变为以BCC为主及少量FCC的混合结构;当x>2.35时,合金形成了单一的BCC结构。Cu促进合金形成FCC结构,而Cr则利于形成BCC结构,然而,当合金体系中同时含有等摩尔比的Cu、Cr两组元时,Cu对合金结构的影响远大于Cr,从而使合金易于形成FCC结构。AlxCoCuFeNi高熵合金的组织形貌随Al含量的增加,由树枝晶形貌向等轴晶转变,合金的硬度也显著增加。

AlxCoCuFeNi high-entropy alloys were designed and prepared to analyze microstructures and mechanical properties.The results reveal that with a relatively lower Al addition（x 〈0.85）,a simple FCC crystal structure is only observed.With increasing in x,the crystal structure is transformed to a mixed structure of BCC and a small amount of FCC.A single BCC structure can be observed with x more than 2.35.It is also found that Cu element promotes the formation of the FCC structure while Cr element favors for the formation of the BCC structure.When Cu and Cr with equal molar ratio are contained in the high entropy alloys,Cu can play a more important role than Cr in selection of the solidification structure.The microstructure of as-cast alloys is varied from columnar dendrite to equiaxed dendritic morphology,so hardness of the as-cast alloys is increased with increasing in Al content.