Influence of substitution of Cu by Ni on the crystallization kinetics of TiZrHfBeCu high entropy bulk metallic glass

The crystallization kinetics of TiZrHfBe(Cu, Ni) high entropy bulk metallic glasses have been studied using differential scanning calorimetry. Each alloy possesses a complex multi-step crystallization process due to the high entropy effect. It was found that substitution of Cu by Ni significantly improves the glass-forming ability but deteriorates the thermal stability of the TiZrHfBeCu alloy. The activation energies of glass transition and crystallization together with the fragility parameter for the Ni-free and Ni-containing alloys have been calculated. According to the calculated values of local Avrami exponent, the first crystallization event for the studied TiZrHfBe(Cu, Ni) alloys is dominated by a direct growth of crystal nuclei. Substitution of Cu by Ni favors the precipitation of Ni-containing intermetallic compounds and inhibits the formation of CuHf2 phase, resulting in the improvement of glass-forming ability.