Mitigating relaxation-induced embrittlement in metallic glasses with multi-component microalloying

Metallic glasses (MGs) are susceptible to embrittlement due to structural relaxation. Microalloying has been explored as a strategy to improve the mechanical properties of MGs. Here it is shown that microalloying with several elements can mitigate embrittlement due to relaxation and even increase plasticity in annealed states. Changes in the glass states with relaxation were studied using X-ray diffraction and differential scanning calorimetry. The mechanical properties of the as-cast and relaxed states were characterised by macroscopic mechanical testing, microindentation, and nanoindentation. Relaxed samples with improved plasticity show more shear events and lower propagation velocities during indentation. Transmission electron microscopy micrographs showed no evidence of crystallization in the annealed samples, suggesting the improvements are due to structural features of the glassy state. This microalloying approach should translate to other alloy systems and aid the wider use of MGs.