Local Structural Evolution of Mechanically Alloyed Mg50Co50 Using Atomic Pair Distribution Function Analysis

Milling-time-dependent local structural evolution of mechanically alloyed Mg 50 Co 50 was investigated by the atomic pair distribution function analysis using both neutron and synchrotron X-ray powder diffraction data. The initial powder mixture was composed of three phases: hexagonal close-packed (hcp) Mg, hcp Co, and face-centered cubic (fcc) Co. As milling progressed, rather rapid reduction in crystallite sizes of hcp Mg and hcp Co along with the formation of the Mg 50 Co 50 phase was observed. Meanwhile, size reduction in the fcc Co phase was found to be relatively gradual, accompanied by heavy strain. Mg 50 Co 50 forms at the early stage of milling and bears an amorphous nature.