Influence of Cu Concentration on Structure, Mechanical Properties and Corrosion Resistance of Ti–Ni–Cu Shape Memory Alloy Ribbons

Abstract

The paper presents the results of investigating the influence of Cu concentration on structure, mechanical properties and corrosion resistance of Ti₅₀Ni_50−xCu_x (x = 0, 5, 10, 15 and 20) alloy ribbons. The ribbons with a thickness of about 25 µm were prepared by using melt-spinning method with a tangential velocity of copper wheel of 40 m.s⁻¹. All the ribbons reveal a single crystalline phase of (Ni,Cu)Ti with the martensitic-B19 structure at room temperature when Cu substitutes for Ni. The structural transformations temperature, tensile strain and elastic modulus increase with increasing Cu concentration whereas the hardness and dislocation density trendly decrease. The corrosion potential E_corr in 3.5% NaCl aqueous solution increases from −0.67 V (for x = 0) to −0.46 V (for x = 20) indicating the better resistance against electrochemical corrosion by Cu addition.

Fig. 5 Stress-strain curvers of Ti₅₀Ni_50−xCu_x (x = 0, 5, 10, 15 and 20) ribbons.