Deformation behavior of Zr33Hf8Ti6Cu32Ni10Co5Al6 high-entropy bulk metallic glass and Cu47Zr47Al6 low-entropy bulk metallic glass at room and high temperatures

Compressive deformation behavior at room temperature and the high temperatures was studied for Zr33Hf8Ti6Cu32Ni10Co5Al6 developed HEBMG and Cu47Zr47Al6 BMG alloys. Compressive strain-stress curves at room temperature showed that with the development of HEBMG, ductility and fracture stress improved by 58% and 5.4%, respectively. The high density of shear bands in the HEBMG compared to the BMG had a significant relationship with their mechanical properties, which indicated that the ductility of HEBMG is higher than BMG. The high temperatures deformation studies were performed at strain rates of 2.5×10−4s−1, 2.5×10−3s−1, and 5.0×10−5s−1 and at temperatures of 710K and 730K. The hot deformation behavior of both alloys was similar, but HEBMG with standed more stresses than BMG (under similar conditions). Considering the free volume theory, for the results obtained from stress-strain curves at high temperatures, the maximum value of activation volume was equal to V = 0.3076 nm3 for HEBMG. Also, viscosity has shown a decreasing trend with increasing strain rate, however HEBMG samples had a higher value of viscosity than BMG samples. Deformation behavior of the HEBMG at high strain rates has been closer to Newtonian flow compared to BMG.