Consolidation and properties of ball-milled Ti50Cu18Ni22Al4Sn6 glassy alloy by equal channel angular extrusion

Ball-milled Ti50Cu18Ni22Al4Sn6 amorphous powders were consolidated by equal channel angular extrusion (ECAE) near the glass transition temperature. A density of about 97% was achieved. The incomplete densification was a result of the powders experiencing insufficient viscous flow as they partially crystallized into the NiTi intermetallic phase during the ECAE processing. Partial devitrification led to a slight increase in the glass transition temperature (Tg) and minor decrease in the crystallization temperature (Tx), when compared with the starting amorphous powders. However, the width of the supercooled liquid region for the ECAE samples remained large, ∼54 K. Under uniaxial compression, the ECAE consolidated samples failed prematurely before yielding due to brittle failure possibly triggered by the pre-existing minor flaws in the specimens, resulting in a much lower compressive fracture strength with respect to that estimated from the microhardness.