How hot is a shear band in a metallic glass?

Abstract

Due to the localization in space and the transience in time, investigations on the shear bands in metallic glasses are extremely difficult. The liquid-like layer frozen on fracture surfaces suggests a decreased viscosity in the shear band. Whether it is resulted from locally heating remains controversial. In this paper, the temperature rise in shear bands is profiled as a function of the duration of shear banding event, the distance from the shear band center and the thickness of shear band. The elastic energies released from the specimen and the testing machine are estimated regarding the serrations with different load drops in the compressive load–displacement curve of a Zr-based metallic glass. The duration of shear event and the released energy by serration are the two main factors determining the temperature rise in shear bands. It is found that both “cold” and “hot” shear bands are attainable. Then the sliding speed, the viscosity and the crystallization probability of shear band are studied. These results can help to better understand and describe the operation of shear band in a quantified and analytical way.