Comalco Aluminum Limited

Peter L Kean

John A Eady

Christopher J Heathcock

Rodney A Legge

Kevin P Rogers

A cast hypereutectic Al-Si alloy with from 12-15% Si, having excellent wear resistance and machinability, improved fatigue strength and good levels of ambient and elevated temperature properties is provided, as well as a method of producing such alloy. The alloy and a melt used in the method contains Sr in excess of 0.10% and Ti in excess of 0.005%, the alloy further comprising: Cu 1.5 to 5.5%, Ni 1.0 to 3.00%, Mg 0.1 to 1.0%, Fe 0.1 to 1.0%, Mn 0.1 to 0.8%, Zr 0.01 to 0.1%, Zn 0 to 3.0%, Sn 0 to 0.2%, Pb 0 to 0.2%, Cr 0 to 0.1%, Na 0 to 0.01%, B (elemental) 0.05% maximum, Ca 0.003% maximum, P 0.003% maximum. Others 0.05 maximum each, the balance, apart from incidental impurities, being Al. The level of Sr in excess of 0.10% and Ti in excess of 0.005% is such that the alloy has a microstructure in which any primary Si formed is substantially uniformly dispersed and is substantially free of segregation, and in which substantially uniformly dispersed Sr intermetallic particles are present but are substantially free of such particles in the form of platelets, with the microstructure predominantly comprising a eutectic matrix.

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Worcester, United Kingdom

Peter L Kean