The ball to powder ratio (BPR) dependent morphology and microstructure ...
K. Ameyama adopted mechanical alloying (MA) process to ball mill W10wt%Re powder and obtained nanoscale W Re powder, which contains nano grain structure with the grain size of 1020 nm [26]. E. Oda et al. used mechanical milling method to obtain 12 nm wide and 25 nm long nanoscale tungsten grain powder [27]. J.