Preparation and high-temperature oxidation behavior of a nanoscale remelting layer on TiBw/TC4 composites by electron beam remelting

Electron beam remelting of composites can effectively improve the strength and hardness of the material surface via regulating the geometry and microstructure of grains and reinforcements. In the present work, the microstructure and high-temperature oxidation behavior of the remelted layer of TiBw/TC4 composites with different heat inputs are systematically investigated. During the whole remelting process, the preferentially precipitated TiBw acts as heterogeneous nucleation site to accelerate the nucleation and growth of TC4 alloy, and are finally pushed to the grain boundary on account of the interfacial energy. Compared with untreated samples, many stacking faults are observed in the remelted nanoscale TiB whisker with the crystal structures of B27 and Bf. It follow as that the surface hardness increases by nearly 40% under the line energy of 96 J/mm (4 mA) because of the smaller network structure TiBw than the parent material, as well as a moderate thickness remelting layer without coarse dendrites. After electron beam remelting treatment, the oxidation resistance of the composite was significantly improved due to the segregation of aluminum on the surface of the remelting layer during oxidation.