Microstructure and mechanical properties of mechanically alloyed Al2O3/Ti-Cu-Ni-Sn bulk metallic glass composites prepared by vacuum hot-pressing

In the present study, Ti50Cu28Ni15Sn7 metallic glass and its composite powders reinforced with 4-12 vol.% of Al2O3 added were successfully prepared by mechanical alloying. In the ball-milled composites, an amorphous matrix with a homogeneous dispersion of Al2O3 particles was developed. The metallic glass composite powders were found to exhibit a large supercooled liquid region before crystallization. The presence of Al2O3 particles did not change the glass formation ability of the amorphous Ti50Cu28Ni15Sn7 powders. Consolidation of the as-milled Ti50Cu28Ni15Sn7 composite powders was performed at a temperature slightly higher than the glass transition temperature under a pressure of ∼1.2 GPa; using this method, the bulk metallic glass composite discs were prepared successfully. However, partial crystallization of the amorphous matrix during the hot-pressing process was noticed. The fracture strength of consolidated composite compacts was increased with Al2O3 additions. The pre-existing particle boundaries may serve as the crack initiation sites which resulted in the brittle failure of the Ti50Cu28Ni15Sn7 BMG composites.