Preparation of metastable precursors with different compositions of Ti–Al–Si by mechanical alloying

With the aim of synthesizing metastable precursors for in situ composite formation in Ti–Al–Si ternary system, five stoichiometric Ti–Al–Si alloys, i.e. Ti–17Al–18Si (all in at.%), Ti–21Al–14Si, Ti–14Al–14Si, Ti–21Al–21Si, Ti–14Al–21Si, were prepared by mechanical alloying (MA) of elemental powder blends for up to 100 h. The structural evolution in these powders was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that elemental powders were progressively transformed into nanocrystalline solid solution and amorphous phases during MA. However, for different contents of Al–Si elements, the behavior of solid-state transformation for the milled powders was quite different, thus distinct precursors could be obtained in each case.