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.