Formation of metal matrix composite layer on aluminum alloy with TiC-Cu powder by laser surface alloying process

Thick hardened metal matrix composite (MMC) layer was formed to improve the wear resistance of a commercial Al-Mg alloy (A5083) plate by using laser s urface alloying with Cu coated TiC powders in the size of between 20 and 40 mum. A continuous wave CO2 laser beam (2100 W) was irradiated on the pre-p laced TiC-Cu powder to melt them together with the substrate in argon atmos phere. The thickness of the MMC layer was approximately 1-2.5 turn. In the MMC layer, TiC particles were not dissolved and were uniformly distributed in the molten matrix. The matrix structure of the MMC layer consisted of th e mixture of the hypo-eutectic, eutectic and hyper-eutectic structures with primary theta (CuAl2) phase and the lump like Cu9Al4 compound and correspo nded to the binary Al-Cu system. The hardness of the MMC layer increased wi th increasing Cu content and the volume fraction of TiC particle, and reach ed approximately HV600 in maximum. The wear resistance of the MMC layer was evaluated by the Ogoshi type wear test as an abrasive wear test with a rot ating counter roller. The wear rate decreased to one-sixth of that of the s ubstrate. The wear resistance of the MMC layer was much better than the Cu alloyed layer without TiC powder and austenite stainless steel SUS304. (C) 2001 Elsevier Science B.V. All rights reserved.