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

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Abstract
Metals and ceramics have contrasting limitations—metals exhibit lower strength and poor high-temperature stability, whereas ceramics are inherently brittle. Materials combining high strength, fracture toughness and thermal stability remain an important scientific objective. Here we report Re–Co–Ta–B bulk metallic glasses (BMGs) that overcome this fundamental limitation, achieving a remarkable fracture strength of about 6.43 GPa while maintaining around 30 MPa m1/2 fracture toughness. This strength value exceeds previously reported values for BMGs and crystalline metals and approaches the strength of advanced ceramics while far exceeding them in toughness. These alloys exhibit pronounced resistance to thermal softening and harsh environments, retaining a strength of 4.4 GPa at 900 K with negligible oxidation and corrosion. Synchrotron measurements and aberration-corrected microscopy reveal the origin of these properties: a unique amorphous structure that inherits a high degree of crystal-like short-range order from the Re7B3 intermetallic phase. First-principles calculations indicate that this atomic framework is strengthened by directional Re–B covalent bonds embedded in a metallic matrix, thereby bridging the ceramic and metallic bonding. This work suggests structural heredity as a guiding principle for engineering next-generation amorphous materials with previously unattainable property combinations.

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