Reverse martensitic transformation and decomposition processes during heating were investigated in Ni-32Al-5Cu (at.%), by transmission electron microscopy (TEM) and differential scanning calorimetry in samples homogenized and quenched from 1300degreesC and hot upset at 1150 degreesC. The hot upset sample revealed reverse martensitic transformation when the homogenized sample underwent transformation of 3R martensite predominantly to the Ni5Al3 phase. To explain these differences in situ heating TEM was performed. (C) 2003 Elsevier Science B.V All rights reserved.