In-situ synthesized Al₃Ti-Al surface composites by friction stir processing

After the surface of 1100-H14 Al alloy plate was machined into rectangular grooves which were then filled with Ti powder, the layer of Al₃Ti-Al composites was obtained by friction stir processing (FSP). The microstructures, phase compositions and hardness of the layer were analyzed by scanning electron microscopy, EDS and X-ray diffraction. The results show that Ti particles are severely broken under the thermal-mechanical coupling process of FSP, and the broken Ti particles rapidly react in situ with Al matrix and synthesize micron or sub-micron particles of Al₃Ti. Owing to the homogeneous distributions of Al₃Ti and residual Ti particles in the Al matrix, the microhardness of the layer reaches 71.39 HV, which is 2.1 times of the base metal.