Some researchers reported that α2 and lamellar phases had major influence on the susceptibility of H to alloys, while H was too low to penetrate the γ-phases. This research focused on the effect of different microstructures obtained from various heat treatments to the diffusion coefficient and mechanical property after H absorption. Modification of γ-TiAl could be achieved by heating as-cast binary samples; Ti–45%Al up to 1200C (above the Te line) and cooled in three different ways: quenched, air-cooled and furnace-cooled. All samples were then subjected to corrosion attack under cathodically charged with galvanostatic mode for 6h. The potential variation with time was monitored from these data the values of the diffusion coefficient of H to γ-TiAl. D was calculated based upon Fick's second law. This result was compared with that obtained from micro-Vickers hardness profiling, which was measured at cross-section area per depth from the top surface corroded. Hydrides formed at the surface were analyzed by using image analyzer, scanning electron microscopy and X-ray diffraction. The results showed that different microstructures had an effect on the diffusion coefficient and mechanical property after H absorption.

Effect of Heat Treatment on the Diffusion Coefficient of Hydrogen Absorption in Gamma-Titanium Aluminide. K.Suardi, E.Hamzah, A.Ourdjini, V.C.Venkatesh: Journal of Materials Processing Technology, 2007, 185[1-3], 106-12