PROCESS OF ALLOYING IN TI-MO SYSTEM BY MECHANICAL ALLOYING AND MIXING OF FE IMPURITY

The mechanical alloying (MA) behavior for beta type solid solutions in Ti-14 mass%Mo and Ti-20 mass%Mo systems was examined by means of X-ray diffractometry (XD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and chemical analysis. The phase transformation and thermal stability of mechanically alloyed solid solutions were also compared with those of the cold-worked powders of the Ti-Mo ingots prepared by melting. Beta phase solid solution was formed by MA and the formation time decreases with increasing Mo content. The further MA causes the appearance of the alpha phase without the formation of the omega phase. On heating the solid solution at temperatures above 823 K, the beta phase was stabilized through the precipitation of the alpha phase. It was also noticed that a great deal of impurity, Fe was dissolved into the powder from the balls and the vessel during the MA process.