Anomalous grain growth in S-doped Ni and comparative insights from the Al-Sn alloy exhibiting grain boundary wetting transition

Abstract Despite considerable body of research on nanocrystalline nickel, the role of sulfur for grain growth in Ni, which is hypothesized to be the cause of the observed abnormal grain growth in Ni, remains unclear. To clarify this issue, in this work, the temperature dependence of the grain size change in pure Ni and S-doped Ni with 50 ppm sulfur was measured. In contrast to pure Ni, S-doped Ni showed anomalous grain size variations with temperature, characterized by a significant growth in the range between 823 and 973 K, a decrease in grain size above 973 K and a renewed growth above 1173 K. The observed anomaly is assumed to be related to the phenomenon of grain boundary wetting and the formation of a liquid (or quasi-liquid) film of S-rich phase at the grain boundaries. For a better understanding and proof of this interpretation, the temperature dependence of grain growth in the alloy of the Al-Sn system was also measured and analyzed, where the wetting transition at different grain boundaries was previously experimentally determined. Graphical abstract