Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
Print version ISSN 0038-223X
POPOOLA, A.P.I.; PITYANA, S.L.; FEDOTOVA, T. and POPOOLA, O.M.. Quantitative study of the hardness property of laser surface alloyed aluminium AA1200. J. S. Afr. Inst. Min. Metall. [online]. 2011, vol.111, n.5, pp.335-344. ISSN 2411-9717.
Aluminium AA1200 was laser alloyed with a combination of nickel and titanium diboride using different weight ratios. Chemical reactions took place with the formation of different phases. The characterization of the alloyed surfaces was carried out by x-ray diffraction (XRD), optical and scanning electron microscopes. The alloyed surfaces are composed of the initial phase of Al-Ni dendrites and eutectics of TiB2/Al and TiB2/Ni distributed on the initial phase. Experimental results obtained showed that Al-Ni intermetallics brought about a significant increase in the hardness property of Al; however, these intermetallics are highly brittle and prone to fail by brittle fracture or stress corrosion cracking when put in service. The addition of TiB2 brought about a reduction in the formation of these intermetallic phases. A microhardness increase of over 10 times the hardness of the substrate was achieved.
Keywords : Dendrites; intermetallics; metal composite; Nd; YAG laser.