Nanocrystalline CoCrFeNiCuAl high-entropy solid solution synthesized by mechanical alloying

The equiatomic multicomponent CoCrFeNiCuAl high-entropy solid solution alloy was synthesized by mechanical alloying (MA). The effects of milling duration and subsequent annealing on the morphology and structure evolution were investigated. Supersaturated solid solution structure can be obtained when the blended powder is ball milled longer than 42 h. The 60 h ball milled alloy powder shows refined morphology and excellent chemical homogeneity. The 60 h ball milled powder exhibits mean particle size of less than 5 μm, which are actually hard agglomerations of nanosized crystalline with crystal size of less than 50 nm. A BCC and a FCC solid solution structure phases appear when the 60 h mechanically alloyed powder was annealed at 600 °C for 1 h, which is attributed to phase precipitation of the metastable supersaturated solid solution. The simple solid solution structure can be maintained even after annealed at 1000 °C.