A study of thermal stability in electrodeposited nanocrystalline Fe-Ni invar alloy

The grain growth of an electrodeposited nanocrystalline Fe-Ni invar alloy was studied with differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results showed very limited grain growth below the temperature of 0.36T(m), and the activation energy was 40 +/- 3 kJ/mol in the low temperature range, which implied the possible mechanism of grain growth as re-ordering of grain boundaries; an abrupt grain growth happened above 0.36T(m) with a DSC exothermic peak detected, of which the heat release was about 14 +/- 2 J/g; at temperatures above 0.36T(m), the grain growth activation energy was obtained through Kissinger analysis and isothermal kinetics analysis, both of the results suggested the grain growth mechanism as grain boundary diffusion. (C) 2011 Elsevier B.V. All rights reserved.