Internal friction of Ni–Ti and Ni–Ti–Cu plates produced by lamination process

Ni–Ti and Ni–Ti–Cu alloys were produced by lamination and diffusion processes. The objective of this study is to understand the mechanism of high damping. These alloys undergo phase transformations. When cooling, elastic modulus decreases and internal friction increases at the transformation temperature, and in the martensite region elastic modulus shows the minimum and a relaxation peak or an increase of background damping is observed depending on conditions. Those behaviors are closely related with dislocation motion at twin interface or slip plane in martensite. It has been proposed that the phase stability, modulus drop and damping capacity due to dislocations are categorized by two electronic parameters B̄0 and Md.