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 gamma-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. (C) 2007 Elsevier B.V. All rights reserved.