Abstract
Surface modification of a Ti-48at%Al alloy was performed by irradiation with a reactive carbon plasma. A relativistic electron beam pre-irradiation was also examined as a pretreatment to the plasma process. The carburization of the alloy was successfully achieved using the plasma process. The carburized surfaces were observed to have a double-layer structure of 15-20 μm in thickness. The top-surface layer was clarified to be mainly composed of TiC and a ternary carbide. An ab initio molecular orbital simulation based on cluster models suggests that Coulombic interactions between the C and proximal atoms play an important role in the rearrangement of atomic configurations to form the reaction products. The top-surface layer exhibited a high hardness and elastic modulus than the sub-surface layer and Ti-48at%Al substrate.
