Fig. 3: Evaluation of the Joule heating effect.

a Real-time temperature profiles of Zr₅₅Cu₃₀Al₁₀Ni₅ (Zr55) bulk metallic glass (BMG) specimens during tensile tests under pulsed currents of different current density, confirming that the specimen temperatures are below the glass transition temperature T_g; b true stress–strain (SS) curves of Zr55 BMG in tension at elevated temperatures in a furnace under no pulsed current; c morphologies of Zr55 BMG specimens after tensile tests at elevated temperatures in a furnace. The specimen tested at 623 K exhibits a brittle fracture via shear banding, in contrast to the elongation and necking of the BMG specimen tested under a pulsed current of a density i = 33 A·mm⁻², of which the specimen temperature is 553 K, even 70 K lower, indicating that the homogeneous deformation of Zr55 BMG under pulsed current is not due to the temperature rise caused by Joule heating effect. The specimen tested at 653 K exhibits necking.