Rapid relaxation and embrittlement of Zr-based bulk metallic glasses by electropulsing

Mechanical relaxation and embrittlement of Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ bulk metallic glasses were achieved rapidly by the direct current electropulsing treatment. The temperature profile was recorded by an infrared camera and it was found to be non-uniform in the treated specimen. Specifically, temperatures below the glass transition temperature, near and above the crystallization temperature could be achieved, respectively, at different locations in the same treated specimen. Two sets of nanoindentation were conducted. While the first set investigated the mechanical properties of three individually electropulsed specimens with different conditions, the second set indented a single treated specimen along its temperature gradient. Both sets of indentation revealed that by Joule heating to different temperatures, relaxation, embrittlement, and crystallization were significantly accelerated by electrical pulses. Results suggest that electropulsing provides an opportunity to simultaneously achieve plastic forming and mechanical property control of metallic glasses.