High temperature deformation behavior of the Zr 41.2Ti 13.8Cu 12.5Ni 10Be 22.5 bulk metallic glass

Abstract

The high temperature deformation behavior of a Zr 41.2Ti 13.8Cu 12.5Ni 10Be 22.5 bulk amorphous alloy has been studied in the temperature range between 351 and 461 °C under compressive as well as tensile loading. Three types of nominal stress–strain curves under compressive loading have been identified depending on the strain rate and test temperature, viz., a linear stress–strain relationship with fracture at the maximum stress, large plastic deformation after stress overshoot, and steady state plastic flow without stress overshoot. The DSC analysis for the compressed specimens was also carried out to determine the change in the crystallization fraction under the various test conditions. Under tensile loading, superplastic-like deformation with a maximum elongation over 500% was observed at 431 °C under a relatively high strain rate of 2×10 −2/s. The tensile test specimens were, however, observed to exhibit a brittle fracture mode at temperatures below the glass transition temperature and above the crystallization temperature under the same initial strain rate. The superplastic-like properties characterized by the low flow stress and large elongation then appear to be very sensitive to test temperature and initial strain rate.