Influence of friction stir processing on the structure and phase state of TiNi alloys

The paper analyzes the effect of friction stir processing (FSP) on the structure and phase state of two titanium– nickel alloys: Ti–50.9Ni and Ti–50.2Ni (at %). The analysis shows that with the FSP modes and equipment chosen, the treatment creates no macroscopic defects in the stir zone, dissolves the initial texture of the alloys, and weakly influences their structure and phase state. In the internal volumes of the track region, Ti–50.9Ni preserves its B2 phase and Ti– 50.2Ni undergoes R → B2 transition with its B19′ phase kept intact. The oxide layer thickness is smaller than 50 µm.