Flaw-insensitive fracture of a micrometer-sized brittle metallic glass

Ruitao Qu, Robert Maaß, Zengqian Liu, Dominik Tönnies, Lin Tian, Robert O. Ritchie, Zhefeng Zhang, Cynthia A. Volkert

Research output: Contribution to journalArticlepeer-review


Brittle materials, such as oxide glasses, are usually very sensitive to flaws, giving rise to a macroscopic fracture strength that is much lower than that predicted by theory. The same applies to metallic glasses (MGs), with the important difference that these glasses can exhibit certain plastic strain prior to catastrophic failure. Here we consider the strongest metallic alloy known, a ternary Co55Ta10B35 MG. We show that this macroscopically brittle glass is flaw-insensitive at the micrometer scale. This discovery emerges when testing pre-cracked specimens with self-similar geometries, where the fracture stress does not decrease with increasing pre-crack size. The fracture toughness of this ultra-strong glassy alloy is further shown to increase with increasing sample size. Both these findings deviate from our classical understanding of fracture mechanics, and are attributed to a transition from toughness-controlled to strength-controlled fracture below a critical sample size.

Original languageEnglish (US)
Article number117219
JournalActa Materialia
StatePublished - Oct 2021
Externally publishedYes


  • Fracture toughness
  • Metallic glass
  • Size effect
  • Small-scale

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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