Liquid-phase separation in undercooled CoCrCuFeNi high entropy alloy

Liquid-phase separation in a CoCrCuFeNi high entropy alloy is evidenced by supercooling method. The CoCrCuFeNi high entropy alloy is supercooled by glass fluxing method with a sample mass about 100 g which allows tensile test at different undercoolings. The microstructure evolution of CoCrCuFeNi high entropy alloy solidified at different undercoolings are investigated. The variation of interdendritic Cu-rich phase and the hardness of the dendrites are described in detail and liquid-phase separation is confirmed to have taken place when undercooling is equal or greater than 100 K. The plasticity and elastic modulus during tensile tests are strongly affected by compositional change upon liquid-phase separation. The samples solidified after liquid-phase separation exhibit much higher plasticity and lower elastic modulus.