Thermal stability of the microstructure of Alloy 718 (TM) Plus has been investigated using the non-isothermal differential scanning calorimetry (DSC) technique. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques are used for microstructural analysis. Samples are heat treated at different temperatures before performing DSC tests. The DSC curves exhibited endothermic and exothermic peaks reflecting in situ changes in the microstructure. The ratio of endothermic to exothermic peak area increased as the preheating temperature increased. (C) 2009 Elsevier B.V. All rights reserved.