Ultrasonic Influence On the Behavior of Shape Memory Alloys

This work is devoted to investigation of the peculiarities of ultrasonic influence on the behavior of shape memory alloys. It is shown that ultrasonic vibrations can initiate shape memory effects as well as modify some functional properties. After ultrasonic treatment the characteristic temperatures are shifted, strain recovery rate and dynamics of shape recovery are changed – at that these and some other changes are depend on the parameters and conditions of ultrasonic influence. The observations using the thermocam showed the maximal temperature was below A_f^σin all cases during the ultrasonic treatment.

We consider the model of the mechanism of ultrasonic influence on shape memory alloys taking into account its heat and power components. The simulation of ultrasound thermal action on mechanical behavior of TiNi alloys showed that temperature increase leads to softening or strengthening of the material depending on its structural state.  The simulation of ultrasound power component showed that alternating stress superposition at the reverse transformation temperatures causes strain recovery and such supplementary stress at the direct transformation temperatures promotes strain accumulation. There is a good correlation between the obtained experimental and model data.