Nanoindentation response of Cu–Ti based metallic glasses: Comparison between as-cast, relaxed and devitrified states

• Nanoindentation tests were conducted on Cu–Ti based melt-spun ribbons.
• The hardness and elastic modulus are enhanced by annealing treatments.
• The highest elastic recovery is achieved for the as-spun ribbon.

Cu36Ti34Zr22Ni8 glassy ribbons were synthesized by melting spinning. The effects of annealing treatments on the microstructure and mechanical properties of this alloy are investigated. Annealing below the crystallization temperature induces a reduction of free volume, as evidenced by differential scanning calorimetry. Annealing at sufficiently high temperatures promotes the formation of stable CuTi, NiTi and Zr–Ti–Cu phases. The as-spun alloy exhibits high hardness (H > 8 GPa), moderate reduced Young's modulus (Er ≈ 90 GPa) and good wear resistance. These properties are enhanced after thermal treatments (H > 13 GPa and Er ≈ 140 GPa are achieved in the fully crystallized sample). The mechanical hardening is accompanied with an increase of the elastic recovery. The influence of free volume on these annealing-induced changes in the mechanical properties is discussed.