Grain growth in a nanocrystalline Ni81P19 alloy

Abstract

Isothermal annealing of a Ni₈₁P₁₉ amorphous alloy performed at 600 K for 1200 s resulted in the formation of a nanocrystalline state with 10 nm average grain size. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements were performed to study the influence of further heat treatments. Linear-heating DSC scan starting from the nanocrystalline state revealed a broad exothermic contribution between 600 K and 770 K, corresponding to a grain-growth process. Isothermal annealing of the nanocrystalline alloy yields the complete formation of fcc-Ni and Ni₃P phases. This process took place by normal grain-growth at low annealing temperatures, while abnormal grain-growth was observed with increasing annealing temperatures.