Solid solubility in nanocrystalline Ti/Mg and Mg/Ti composites powder produced by mechanical alloying

Mechanical alloying(MA) was examined by ball-milling the mixed starting powder of various composition, Ti-10, 20, 30, 40, 50, 60, 70, 80, 95at%Mg plus 2mass%NaCl powder. NaCl powder was an excellent anti-sticking agent for MA. The process of MA was mainly followed by X-ray diffraction method. Super-saturated quasi solid solution was formed for the samples up to 60at%Mg. The single hcp structure was newly created up to 30at%Mg samples, and over this composition range hcp peaks were combined to the diffraction pattern which will lead to bcc like nano-crystallite. In Mg rich side, Ti-70∼95at% MA samples showed the coexistence of hcp phases, Ti-based and Mg-based dilute solid solution. The solubility was estimated from the change of lattice constant. But it was somewhat difficult to detect the alloying effect of MA on Mg and Ti in Ti-95at%Mg sample. MA samples, Ti-20 and -50at%Mg, showed the starting of phase separation due to one hour annealing at 673 and 473K, respectively.