Mechanically milling-induced amorphization in Sn-containing Ti-based multicomponent alloy systems

Two Sn-containing Ti-based multicomponent alloys, Ti50Cu35Ni12Sn3 and Ti50Cu18Ni22Al4Sn6, were chosen to investigate the amorphization of pre-alloyed fragments under high-energy ball milling. For comparison, the amorphous alloy ribbons with the same compositions were also prepared using melt-spinning method. Amorphous nature of the as-prepared samples was characterized using X-ray diffraction, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). For the ball-milled (BM) Ti50Cu35Ni12Sn3 alloy, the glass formation is predominant but a small fraction of the α-Ti nanocrystals still remains unreacted. In contrast, the complete amorphization can be achieved in the ball-milled Ti50Cu18Ni22Al4Sn6 alloy. In both cases, thermal properties of the ball-milled glassy alloys are comparable to those of the melt-spun (MS) glasses, exhibiting a distinct glass transition and wide supercooled liquid region about 60 K. The amorphization extent in the final milled products is associated with whether the α-Ti phase exists in the initial microstructure of the alloys as starting materials.