Temperature rise from fracture in a Zr-based metallic glass

Inhomogeneous serrated plastic flow and the subsequent fracture of a Zr-based metallic glass are probed by high-speed in-situ pyrometry and in-situ acoustic emission. Whilst the temperature rise during serrated flow remains below the detection threshold of 300 °C, fracture is accompanied by ΔT of up to approximately 600 °C within less than 100 μs. Heating rates during fracture are up to 10⁷ K/s, for which a dynamic glass transition temperature can be determined. A continuous wavelet analysis of the acoustic-emission pulse from fracture reveals an intermittent crack propagation with phases of intense activity of ca. 5–15 μs. These findings quantify the final stage of a shear-band-to-crack transition in terms of time scales and temperature excursions, the latter of which remains well below the melting temperature of the material in this study.