Ceramic-like strength and metallic toughness in a bulk metallic glass

a, Schematic illustration of the compositional design of a BMG. The upper panel shows the landscape of the liquid-crystal entropy difference for the Co-Ta, Co-B, and Re-B systems, where the circles position the phases selected in terms of the low melting entropy principle. The red dashed line represents Richard’s rule on the melting entropy of metal elements, which is approximately 1.1 R48, with R being the universal gas constant. The lower left panel shows the compositional design route of Re 26.9 Co 44.1 Ta 6.9 B 22.1 alloy (Re1), by balancing three binary phases with inherently low melting entropies: Re 55 B 45 (eutectic), Co 2 B (intermetallic), and Co 86.5 Ta 13.5 (eutectic). The lower right panel displays a series of Re-Co-Ta-B alloy rods fabricated via copper mold casting after composition optimization of the Re1 alloy. b, XRD patterns confirming the fully amorphous nature of the as-cast samples. c, DSC curves, with marked T g and T x , indicating the thermal stability of the developed alloys. d, Relationship between d c × T g and d c × ΔT x for known high-temperature BMGs. e, Correlation between T x and activation energy of crystallization for various BMGs. Detailed data are shown in Supplementary Tables 6 and 7.