Estimation of critical cooling rates for glass formation in bulk metallic glasses through non-isothermal thermal analysis

Critical cooling rate (R_c) for glass formation has been calculated from an integrated transformation curve, constructed by combining continuous cooling transformation (CCT) and continuous heating transformation (CHT) curves. The CCT and CHT curves were calculated from experimental measurements on cooling rate dependence of solidification onset temperature using classical nucleation kinetics and heating rate dependence of crystallization onset temperature using Kissinger method, respectively. The critical cooling rate was calculated from the intersection point of the two curves, corresponding to an apparent nose point in the integrated transformation curve. The calculated critical cooling rates were in good agreement with those measured for five different bulk glass forming alloys of Ca-Mg-Zn, Pd-Ni-Cu-P, Zr-Ti-Cu-Ni-Be and Mg-Cu-Y alloys.