Glass Forming Ability, Crystallization And Finite Element Simulation Of Tension Test Of Zr-based Bulk Metallic Glasses

The enhancement of GFA of Bulk Metallic Glasses (BMGs) has been drawing increasing attention in recent years due to their scientific significance. In this work, the glass forming ability of Zr46Cu37.64-xAg8.36Al8Bex (x=0,6 and 10 at.%) BMGs were significantly improved by Be addition. The critical size of amorphous rods can be over 35 mm diameter. The high GFA achieved is mainly due to the decrease of the melting point and liquidus temperature, and suppression of the formation of crystalline phases during solidification from liquid state. The high stabilization with supercooled liquid regime of 115 K was found for the BMG with x=10 at.%. Two independent exothermic events happen in x=0 and 6 at.% BMGs, corresponding to the formation of primary crystalline phases Cu10Zr7 and AgZr, then transforming to final stable crystalline phases Zr2Cu and AlCu2Zr. However, in the x=10 at.% BMG, the precipitation of primary phases and transformation to final stable phases are within the first exothermic event and the AlCu2Zr phase is totally suppressed.Plastic deformation of BMGs closely relies on the formation and evolution of shear bands. To investigate the initiation and evolution of shear bands in tension, scanning electron microscope (SEM) equipped with an in-situ tension stage was used for a Zr64.13Cu15.75Ni10.12Al10 BMG, and corresponding calculation using finite element method was realized. The results suggested that the shape of tensile specimen and corresponding tension-induced stress gradient has an important role in the evolution of shear bands of BMGs.