Surface crystallization of melt-spun Pd40Ni40P20 glass

The crystallization of Pd₄₀Ni₄₀P₂₀ glass, produced by melt-spinning in air, has been studied by optical metallography. Crystallization is predominantly from the surface and is more prevalent on the wheel-side. The non-uniformity is attributed to variation in quench rate during production. A three-stage anneal permits crystals which have nucleated at the surface to be identified and their size distribution to be analysed. The surface nucleation is heterogeneous and appears to be hindered by mild oxidation. The annealing atmosphere markedly affects the surface crystallization behaviour, as does removal of the original ribbon surface. When nucleation is sparse, partial crystallization causes the development of noticeable relief on the sample surfaces.