Themechanical activation also resulted in a decrease in the particle
size, Fig. 2. In detail, the d50 and d90 of sintered powder were 7 μm and
18 μm, respectively, and were reduced to 1 μm and 6μm, respectively,
after the mechanical activation. Concurrently, the BET specific surface
increased from 3.1m2/g to 6.2m2/g after mechanical activation.