Origin of the Simultaneous Improvement of Strength and Plasticity in Ti-based Bulk Metallic Glass Matrix Composites

Abstract

W-rich particle-reinforced Ti-based bulk metallic glass (BMG) matrix composites with a compressive strength approaching 3 GPa and a fracture strain of approximately 12% were developed. In contrast to most existing BMG matrix composites, in which the improved ductility was obtained only at the expense of the strength, the composites developed in this study exhibited a significant enhancement in their strength, as well as an improvement in the plasticity. This improvement in the plasticity was attributed to the blocking and circumscription of the shear band propagation, leading to the formation of a large number of shear bands. Using a classical elasticity theory of inclusions, the improvement of the strength was interpreted as resulting from the generation of tensile residual stresses in the matrix due to the difference in the coefficient of thermal expansion between the W-rich particles and the BMG matrix.