Effects of thermal cycling on multiple-stage transformation in Ti49.3Ni50.7 shape memory alloy

The effects of thermal cycling on multiple-stage transformation in Ni50.7Ti49.3 alloy were directly studied by DSC and in situ TEM observations. The phase transformations in the grain interior were suppressed during thermal cycling, whereas the regions along grain boundaries retained their original characteristics. According to in situ observations, the heterogeneous precipitates that concentrated along grain boundary areas may account for the different evolutions of transformations during thermal cycling.