PROPERTIES OF REACTIVELY CAST ALUMINUM-TIB2 ALLOYS

A salt base reactive casting process has been employed to produce A356 aluminium casting alloys containing fine dispersions Of TiB2. These h ave been compared with commercially available Duralcan A356 material w ith SiC particles which have also been incorporated by a casting techn ique. Structural, mechanical, and wear properties have been measured. These show that TiB2 is extremely effective in enhancing modulus in ad dition to significantly reducing the coefficient of friction when used against an alloy steel plate. The wear rate of the alloy is found to be independent of particle type but is governed mainly by volume fract ion, as is the load transition from mild to severe wear. However, the wear mechanisms for TiB2 and SiC composites are different when the ste el disc is taken into account and the wear debris examined. The plate is effectively machined by SiC, resulting in extensive damage of the m ating plate. Alloy A356 with TiB2 additions is made by reactive castin g a simple alloy to process and is thereby a viable alternative to low cost Al-SiC cast composites. (C) 1993 The Institute of Materials Manu script received 2 March 1993; in final form 5 May 1993.