Authors:
L. Mabhali
Council for Scientific and Industrial Research, National Laser Centre, P.O. Box 375, Building 46F, Pretoria 0001, South Africa and School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa

S. Pityana
Council for Scientific and Industrial Research, National Laser Centre, P.O. Box 375, Building 46F, Pretoria 0001, South Africa

N. Sacks
School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa

Laser alloying of aluminum AA1200 was performed with a 4.4 kW Rofin Sinar Nd:YAG laser to improve the surface hardness. Alloying was carried out by depositing Ni, Ti and SiC powders of different weight ratios on the aluminum substrate. The aim was to form surfaces on aluminum reinforced with metal matrix composites and intermetallic phases. The laser parameters used were 4 kW power and 10 mm/s laser scanning speed. The microstructures formed were examined using optical and scanning electron microscopes and the phases were identified with x-ray diffraction and energy dispersive x-ray analytical techniques. Preliminary results showed that the microstructure of the alloyed layer depends on the content of Ni, Ti and SiC in the deposited powder mixture. The distribution of the SiC particles was not homogeneous. Intermetallic phases were formed between Al-Ni-Ti-SiC during laser alloying. An increase in surface hardness was achieved after laser alloying. A surface hardness of approximately 356.8±43.4 HV_0.1 was achieved after alloying with a powder containing 70 wt % Ni, 20 wt % Ti and 10 wt % SiC. The increase in hardness was attributed to the formation of the intermetallic phases.