Effect of High-Pressure Torsion on the Thermal and Mechanical Properties of La ₆₂ Cu ₁₂ Ni ₁₂ Al ₁₄ Bulk Metallic Glass

Even though bulk metallic glasses (BMGs) are generally brittle, they receive large plastic deformations of over 1000% shear strain without fracturing through the application of combined shear and hydrostatic stresses. In this study, the effects of the severe plastic deformation by high-pressure torsion (HPT) on the thermal and mechanical properties of La ₆₂ Cu ₁₂ Ni ₁₂ Al ₁₄ BMG are investigated. Crystallization is not detected during the HPT processes with 5, 15, and 30 revolutions. However, increase in glass transition temperature, crystallization temperature, fracture strength, and fracture strain, and decrease in the coefficient of thermal expansion and hardness due to the HPT process are found. These changes in the properties are attributable to the increased free volume that results from the rejuvenated structure in the HPT-processed BMG. In addition, the fracture in the HPT-processed La ₆₂ Cu ₁₂ Ni ₁₂ Al ₁₄ BMG proceeds through a softening mechanism in the microscale region.