Process for producing a cast article from a hypereutectic aluminum-silicon alloy

Abstract

A process for making a cast article from an aluminum alloy includes first casting an article from an alloy having the following composition, in weight percent: Silicon (Si) 14.0-25.0 Copper (Cu) 5.5-8.0 Iron (Fe) 0-0.8 Magnesium (Mg) 0.5-1.5 Nickel (Ni) 0.05-1.2 Manganese (Mn) 0-1.0 Titanium (Ti) 0.05-1.2 Zirconium (Zr) 0.12-1.2 Vanadium (V) 0.05-1.2 Zinc (Zn) 0-0.9 Phosphorus (P) 0.001-0.1 Aluminum balance In this alloy the ration of Si:Mg is 15-35, and the ratio of Cu:Mg is 4-15. After an article is cast from the alloy, the cast article is aged at a temperature within the range of 400° F. to 500° F. for a time period within the range of four to 16 hours. It has been found especially advantageous if the cast article is first exposed to a solutionizing step prior to the aging step. This solutionizing step is carried out by exposing the cast article to a temperature within the range of 875° F. to 1025° F. for a time period of fifteen minutes to four hours. It has also been found to be especially advantageous if the solutionizing step is followed directly with a quenching step, wherein the cast article is quenched in a quenching medium such as water at a temperature within the range of 120° F. to 300° F. The resulting cast article is highly suitable in a number of high temperature applications, such as heavy-duty pistons for internal combustion engines.

Dependencies are inferred from the claim text.