Local structural evolution of mechanically alloyed Mg₅₀Co ₅₀ using atomic pair distribution function analysis

Milling-time-dependent local structural evolution of mechanically alloyed Mg₅₀Co₅₀ 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 Mg₅₀Co₅₀ phase was observed. Meanwhile, size reduction in the fcc Co phase was found to be relatively gradual, accompanied by heavy strain. Mg₅₀Co₅₀ forms at the early stage of milling and bears an amorphous nature.