Structure and hardness of surface of Al18B4O33w/Al composite by laser surface melting

As a new material, aluminum borate whisker reinforced aluminum composites have attracted interest and have been considered for a wide range application because of their high specific strength, high modulus and low cost. The study included a detailed characterization of the laser melting surface in terms of microstructures, phase analysis and a ratio of Al₂O₃ (the decomposition products of whiskers during laser process) and Al in intensity with tests parameters as an indication of Al₂O₃ distribution. Microhardness of the laser layer was also studied in detail. The results indicated that the most of γ-Al₂O₃ exists at the bottom of the laser pool, which led to a maximum value in the hardness be obtained. Microhardness of the laser layer was improved to 294 Hv as compared to 178 Hv of the as-cast composite, because of the existence of Al₂O₃ particles, solid solution hardness and the grain refinement of the laser layer following rapid quenching associated with the process.