The effect of tensile deformation on the damping capacity of NiTi shape memory alloy

The vibration damping capacity of a near-equiatomic NiTi shape memory alloy was characterized as a function of tensile deformation by utilizing dynamic mechanical analysis. The intrinsic internal friction (IF) values of the martensite phase (Q(int,m)(-1)) decreased 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. A two-stage behavior was observed in terms of the IF values of the transformation peak. IF reached a peak value at 4%, dropped at 5% and monotonically increased again up to 10% deformation. Thermal cycling partially restored Q(int,m)(-1) levels and shifted the transformation peak close to its undeformed IF and temperature values during the second reverse transformation. (C) 2016 Elsevier B.V. All rights reserved.