High temperature deformation behaviors of Ti40Zr25Ni3Cu12Be20 bulk metallic glass

Compressive deformation behaviors of a cast Ti40Zr25Ni3Cu12Be20 bulk metallic glass in the test temperatures ranging from 428 to 658 K were examined in a broad range of strain rates from 1.3 × 10−4 to 3 × 10−2 s−1. The alloy studied exhibits an extraordinary compressive superplastic formability within the supercooled liquid region, typically evidenced by a large compressive strain up to 0.83. The superplastic flow behaviors are strongly dependent on the test temperatures and applied strain rates. At low temperatures or high strain rates, the viscosity measured is found to dramatically decrease with increasing strain rate (i.e., non-Newtonian flow) and a stress overshoot is detected in the first steps of strain. At low strain rates or high test temperatures, the studied glass exhibits a Newtonian flow behavior. The value of activation volume increases with increasing test temperatures.