Ternary Co-Mo-B bulk metallic glasses with ultrahigh strength and good ductility

Abstract

In this work, novel ternary Co100-x-yMoxBy (at.%, x = 18–28, y = 11–17) bulk metallic glasses (BMGs) with ultrahigh strength and good ductility were developed by copper mold casting technology. The best glass former of the marginal BMG chemical composition was Co64Mo22B14 with a maximum critical size up to 2 mm in diameter. It revealed that the compressive strength and plastic strain of Co-Mo-B ternary BMGs were 4630–5400 MPa and 0.8–5.1%, respectively. The intrinsic strengthening mechanism was the network-like atomic configurations that could act as the origins for high resistance against plastic yielding. The good plasticity was mainly attributed to the glassy alloys containing a large amount of randomly distributed free volume with a high Poisson's ratio.