Effect of Ag substitution for Ti on the deformation behaviors of in-situ Ti-based bulk metallic glass composites

Four Ti53-xZr20Nb10Cu5Be12Agx (x = 0, 1, 3 and 5 at.%) bulk metallic glass composites (BMGCs) with various size, volume fraction and morphology of in-situ crystal phase were prepared by the arc-melting method. The shear bands extensions under strain of 5% and 20% were observed to explore the contributions of in-situ crystal phase on the deformation behaviors. The results showed that addition of Ag element significantly increased the glass forming ability. When Ag addition increased from 0 to 5 at.%, the volume fraction of in-situ crystal phase decreased from 74.5% to 38.3%, the morphology transformed from the dense cluster to the spotted shape, resulting in the decrease of dendrites span length (L) and the increase of dendritic arm spacing (DAS). The size, volume fraction and morphology of in-situ crystal phase had great influence on the initiation and extensions of shear bands. In the in-situ BMGCs, the crystal phases with the appropriate size, volume fraction and morphology were conducive to the initiation of multiple shear bands and could effectively restrain the expansion of single shear band, improving the plasticity, and the in-situ BMGCs with Ag element of 3 at.% exhibited the highest plasticity of 17.9%.