THEORETICAL DETERMINATION OF TWIN BOUNDARIES IN R-PHASE OF Ni-Ti SHAPE MEMORY ALLOYS

Twin boundaries among different variants in Nitinal R-phase were determined using group decomposition theory. It was found that there are four variants in the R-phase. The four variants may form three types of self-accommodation group. The four variants are twin related with l00_p and l00_p as twin planes. These results are in good agreement with the experiment data.