TRANSACTION PAPER

Quantitative study of the hardness property of laser surface alloyed aluminium AA1200

A.P.I. Popoola^I; S.L. Pityana^{I, II}; T. Fedotova^I; O.M. Popoola^I

^ITshwane University of Technology, Pretoria, South Africa
^IICenter for Scientific and Industrial Research-National Laser Centre, Pretoria, South Africa

SYNOPSIS

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

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