Effect of annealing and cobalt content on relaxation and crystallization behavior of zirconium based bulk metallic glasses

The effects of annealing and cobalt content on relaxation and the crystallization process of Zr-64.Ni(10)A(17)Cu(19) bulk metallic glasses were investigated. beta-relaxation occurs during annealing, leading to increased endotherm before crystallization. alpha-relaxation during high temperature annealing (higher than Tg) affects the crystallization process. The introduction of cobalt leads to an inhomogeneous amorphous structure and two-step crystallization due to the positive mixing enthalpy between cobalt and copper. Non-affine thermal strain arising from low temperature annealing of heterogeneous structure leads to a reduced endotherm phenomenon during relaxation on the DSC curves and a reduction in hardness.