Tailorable Damping Capacity in NiTi Shape Memory Alloy

The vibration damping capacity of a near-equiatomic NiTi shape memory alloy (SMA) was characterized as a function of tensile deformation by utilizing dynamic mechanical analysis. The intrinsic internal friction (IF) values of the martensite phase decreased monotonically with increasing deformation levels up to 10%, attributed to a decrease in the density of martensite variant and twin boundaries. Deformation increased the temperature of the transformation peak during the first reverse transformation of thermal cycling. Thermal cycling partially restored the IF levels of martensite and shifted the transformation peak close to its undeformed IF and temperature values during the second reverse transformation. The results of this study showed that IF of NiTi SMAs is highly dependent on the amount of internal interfaces, which can be tailored through tensile deformation for specific damping applications.