Achieved improvement of damping capacity in TiNi shape memory alloy through He-ion irradiation

Abstract Ti Ni shape memory alloys have been widely used to eliminate noise and mechanical vibrations. However, narrow working temperatures and low damping performance limit its applications. Here, a high damping capacity with the relaxational internal friction close to 0.0524 at 5 Hz and the intrinsic internal friction close to 0.04512 are detected after He ion irradiation. The internal friction value greater than 0.02 in a wide working temperature range of 200 K is reported. Further analyses indicate the critical role of He ion irradiation in increase of damping property. We demonstrate that the high broad internal friction could be derived from the interaction between He/H atoms and martensite twinning interface, and the change in twinning type (11 1 ¯ ) type I twinning to (001) compound twinning in the irradiated layer. The He ion irradiation strategy disclosed in the current work is expected to be a promising way to design high damping alloys.