On the grain growth behaviour of Ni–W alloys in the extremely fine-grained regime

Nanocrystalline pure FCC metals and alloys are known to exhibit abnormal grain growth. A normal grain growth is not expected given the presence of substantial driving forces and even more so at extremely fine grain sizes, i.e. less than 10 nm. While several groups have investigated improved grain size stability in Ni-based binary alloys owing to the addition of solutes, grain growth behaviour remains unexplored. In the present study, nanocrystalline Ni–W alloys with 8 and 15 at% W are examined in the grain size regime below 10 nm. Normal grain growth behaviour is observed among these alloys annealed at 773 K, evidenced from (a) parabolic kinetics in plots of the square of average grain size against annealing time, and (b) statistical self-similarity on the scaled size distribution in a log-normal plot.