It is important to note that σms is dependent on parameters such as temperature and the number of nucleation sites for phase nucleation. Interfaces and inclusions will provide general sites for the transformation to begin, and if these are great in number, it will increase the driving force for nucleation. A smaller σms will be needed than for homogeneous nucleation. Likewise, increasing temperature will reduce the driving force for the phase transformation, so a larger σms will be necessary. One can see that as you increase the operational temperature of the SMA, σms will be greater than the yield strength, σy, and superelasticity will no longer be observable.