On equilibrium ga intergranular films in Cr2GaC

Abstract

The presence of equilibrium intergranular films (IGFs) in metallic systems has long been postulated; compelling evidence for this idea, however, is still lacking. Herein differential scanning calorimetry, in the-60°C to70°Ctemperature range, on bulk and Cr2GaC powders was carried out. A sharp endothermic trough, roughly 50°C below the melting point of bulk pure Ga, in the powdered samples was taken to be strong evidence for the presence of IGFs in the latter. The troughs for the sintered body were much more diffuse suggesting that in this case, a distribution of grain boundary thicknesses exists. A temperature dependent adsorption energy is postulated to explain the reversible extrusion and resorption of 100µm thick Ga micro-pillars. © 2013 ZhengMing Sun, Michel W. Barsoum, Yamei Zhang, Hitoshi Hashimoto.