To find a clear understanding between elastic energy stored in the alloy during forward martensitic tramsformation and temperature range of martensitic transformation (Af-As or Ms-Mf) please see the paper on thermodynamics of martensitic transformations
R. J. Salzbrenner and M. Cohen, Acta Metall. 27, 739 (1979).
Please, don't do the question in such a way that we need to read such paper. After read careful such paper, you shoul do a precise question, eventually with a figure.