Some nonlinear and linear elastic properties of Ni40Ti50Cu10 near the martensitic transformation

Linear and nonlinear elastic effects occuring in a single crystal of the ternary alloy Ni₄₀Ti₅₀Cu₁₀ were determined with a modified ultrasonic pulse echo-overlap technique at different temperatures. All linear elastic coefficients could be measured above and below the martensitic transformation supplementing the results of [A. Alippi (Ed.), Proceedings of the International Conference on Acoustics, Rome, 2001]. A large jump of the elastic stiffness c₄₄ could be detected. First nonlinear elastic measurements were performed. No substantial increase of anharmonicity could be found. The maximum stress amplitude was held far below the yield stress of the material.