Crystallization and thermal stability of Ni-based metallic glass with high tungsten and boron

Non-isothermal crystallization behavior of the amorphous (Ni51W31.6B17.4)(75)Co-25 alloy with high tungsten and boron content was investigated. Continuous heating DSC analyses of the amorphous samples revealed that the alloy undergoes crystallization with three-step. The thermal stability and crystallization kinetics of the samples were evaluated by Lasocka, Kissinger and Ozawa approaches. Activation energy calculated for the first crystallization step showed that the thermal stability of the NiCoWB alloy is higher than other Ni-based alloys. Avrami exponent value calculated for the early stage of the Ni-ss- phase crystallization indicated a three-dimensional diffusion-controlled mechanism with increasing nucleation. The continuous heating transformation diagram plotted according to non-isothermal analyzes is consistent with the phases detected in isothermal heat treatments. The usability of the continuous heating transformation diagram of the alloy in isothermal heat treatment applications has been demonstrated.