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The deformation of NiTi shape memory single crystals are reported under compression loading for selected crystal orientations and two different Ti₃Ni₄ precipitate sizes. For the [148] orientation, selected for highest recoverable strains, the peak aging treatment decreased the transformation stress from austenite to martensite. At the same time, peak aging raised the flow stress of both the austenite and martensite compared to the overaged case by increasing the resistance of the material to dislocation motion. The transformation proceeds beyond the stress plateau region and extends until martensite yielding occurs. This results in recoverable strain levels equivalent to the theoretical estimate of 6.4%. The [112] orientation was chosen to produce two variant formations and in this case, the transformation proceeded over an ascending stress–strain curve compared to the nearly plateau response for the [148] case …