Effect of Titanium on Homogenizing Process and Microstructure of Alloy 2618

摘要

The effect of titanium on the homogenizing process of alloy 2618 and the microstructure of the Ti-containing alloy before and after homogenization has been investigated using optical microscope (OM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), differential thermal analysis (DTA). The results show that the addition of 1.5 mass% Ti to alloy 2618 could refine its grain size remarkably. A large amount of rod-shape Al_3Ti particles with the size range of 2-12 μm distribute evenly and dispersively in the alloy. It is θ (Al_2Cu) phase instead of S' (Al_2CuMg) obtained in eutectic structures due to the non-equilibrium solidification in casting of 2618-Ti alloy, which is the same as alloy 2618. The optimal homogenization temperature (773 K) for Ti-containing alloy 2618 (2618-Ti alloy) is the same as that of alloy 2618. Combining the results of kinetic analysis and experiments, the optimized homogenizing time for Ti-containing alloy 2618 at 773 K is only 12 h, which is shorter than that for alloy 2618. The shortening of the optimized homogenizing time results mainly from the decrease of the grain size of 2618-Ti alloy.