Strengthening of multicomponent glass-forming alloys by microstructure design

The combination of high strength with high elastic strain renders bulk metallic glasses (BMGs) or nanostructured Zr-base multicomponent alloys attractive candidates as advanced high-strength materials for structural applications. To circumvent the limited ductility of these glassy alloys, we prepared a heterogeneous microstructure combining glassy or nanostructured matrix along with a dendritic second-phase particles. The alloys were designed by adding different amounts of Nb to the Zr-based multicomponent glass-forming alloy system. The refractory metal Nb promotes the formation of a primary bcc β-Zr phase having dendritic morphology while the residual melt solidifies to a nanostructured/amorphous matrix. A correlation between the alloy composition and adopted casting method with evolved microstructures and mechanical properties is revealed. These composites exhibit a unique combination of high fracture strength up to 1922 MPa as well as plastic strain over 15.8% under uni-axial compression testing at room temperature. We emphasize the possibilities to tailor such composite microstructures in favor of either strength or ductility, or a combination of both, and also discuss the acquired ability to synthesize such in situ composite microstructures in bulk form through inexpensive processing routes.