Composition design and properties of Cu–Zr–Ti bulk metallic glass composites

Highlights: • The studied CuZr-based BMGCs display work-hardening behavior. • The studied Cu-based BMGCs exhibit step-like anodic polarization behavior. • The corrosion behavior tranforms from self-passivization to pitting corrosion. -- Abstract: (Cu₅₀Zr₅₀)_x(Cu₇₃Ti₂₇)_100-x (x = 0.63–0.75 at.%) alloys are designed using the proportional mixing of Cu₅₀Zr₅₀ and Cu₇₃Ti₂₇ binary alloys. Their thermal, mechanical and corrosive properties as well as the glass forming ability (GFA) are systematically investigated. The results show that the studied Cu-based glass forming alloys are bulk metallic glass composites (BMGCs) with off-eutectic compositions and display work-hardening behavior. The glass transition temperature and the reduced glass transition temperature increase and then decrease with increasing x when x ≥ 0.74 at%, while on the contrary for the critical cooling rate and supercooled liquid region. Both yield strength and fracture strength firstly increase and then decrease with decreasing x when x ≤ 0.71 at%. The plastic strain of (Cu₅₀Zr₅₀)_0.75(Cu₇₃Ti₂₇)_0.25 BMGC is the largest among the studied Cu-based BMGCs. Potentiodynamic polarization measurements show that all studied BMGCs exhibit a step-like anodic polarization behavior, indicating two competitive procedures of pitting corrosion and self-passivization. The corrosion behavior gradually transforms from predominant self-passivization to the pitting corrosion with decreasing x. Both corrosion current density and onset passive current density of (Cu₅₀Zr₅₀)_0.75(Cu₇₃Ti₂₇)_0.25 BMGCs are two orders of magnitude lower than those of the other Cu-based BMGCs. The mechanisms for the GFA and the corrosion are also discussed. The present work would shed light on how to design and develop BMGCs with superior comprehensive performances.