Supercooling investigation and critical cooling rate for glass formation in Pd-Cu-Ni-P alloy

Based on the previous results of undercooling investigation, the critical cooling rate for glass formation (R_c) and crystallization behavior of the Pd₄₀Cu₃₀Ni₁₀P₂₀ alloy are determined and compared with theoretical calculation results using the classical nucleation theory (CNT). As nucleating homogeneously, the R_c is evaluated to be 2.08×10^-5 K/s under continuous cooling, which is underestimated by four orders of magnitude against the experimental results. Actual crystallization of the alloy is dominated by a heterogeneous nucleation mechanism. Considering foreign substrate-induced nucleation, the wetting angle (θ) between crystalline embryo and undercooled melt is evaluated to be about 62.5°. Furthermore, other heterogeneous nucleation mechanisms beyond the CNT are discussed to fit the experimental results.