K. Pajor; M. Jain; T. Koziel; D. Pikulski; P. Bała; J. Michler; K. Wieczerzak
SSRN 5117190 (2025)
This study compares the mechanical behaviour of fully amorphous Zr50Cu37Ag13 and partially amorphous Zr42Cu40Ag18 alloys at micro and macro scales using micropillar and bulk compression tests. Both alloys, synthesized via arc melting, were tested at strain rates from 10− 4 to 10− 1 s− 1. Micropillar tests showed significant plastic deformation with serrated flow, yielding strengths of 1468–1590 MPa for Zr50Cu37Ag13 and 1512–1758 MPa for Zr42Cu40Ag18. Bulk tests revealed limited plasticity, with Zr42Cu40Ag18 exhibiting brittle fracture due to the crystalline Zr2Ag phase. Negative strain rate sensitivity (SRS) was observed in all micropillar tests and in Zr50Cu37Ag13 bulk samples, while Zr42Cu40Ag18 bulk samples displayed positive SRS. Analysis of serrated flow in micropillars revealed significant stress drops (Δσ) that increased with decreasing strain rate, indicating active shear band formation and propagation. Negative SRS is attributed to adiabatic shear banding, where localized heat generation at high strain rates softens the material, facilitating shear band formation. Positive SRS in Zr42Cu40Ag18 bulk samples likely results from the Zr2Ag phase, which reduces deformation localization, promotes uniform stress distribution, and activates additional plasticity mechanisms. Smaller stress drops in bulk samples stem from more dispersed deformation, better heat dissipation, contrasting with the highly localized deformation in micropillars. Fracture morphologies revealed vein-like patterns in Zr50Cu37Ag13 and mixed features in Zr42Cu40Ag18, demonstrating the influence of sample size and composition on mechanical behaviour.