Piston with tailored mechanical properties

A cast aluminum alloy piston for internal combustion engine, comprising a crown region subjected to relatively higher service temperature than other regions of said piston, said crown region having a microstructure including ceramic reinforcing material and platelet precipitates and said other regions having a microstructure comprising spheroidal precipitates.

A method of making a piston for an internal combustion engine, comprising introducing molten matrix-forming alloy into a casting mold including reacting a ceramic reinforcing material and said molten matrix-forming alloy at a crown-forming region of said casting mold to locally alter alloy composition in said crown-forming region, solidifying said alloy to form a cast piston having a crown region and other regions, and precipitation hardening said cast piston whereby said locally altered alloy composition yields strengthening precipitates at said crown region providing strength properties suited to said higher service temperature by virtue of said precipitates having better resistance to averaging during engine service compared to different precipitates formed by the unaltered alloy composition at said other regions of the cast piston, said different precipitates providing strength properties suited to relatively lower service temperatures at said other regions.

A method of making a piston for an internal combustion engine, comprising introducing a molten matrix-forming aluminum alloy including magnesium into a casting mold including reacting a ceramic reinforcing material and said magnesium of said molten matrix-forming aluminum alloy at a crown-forming region of said casting mold in a manner to locally alter alloy composition by reducing magnesium concentration thereof residing in said crown-forming region, solidifying said alloy to form a cast piston having a crown region and other regions, and precipitation hardening said cast piston whereby said altered alloy composition having reduced magnesium concentration yields precipitates at said crown region providing strength properties suited to higher service temperature by virtue of said precipitates having improved resistance to averaging during engine service as compared to different precipitates formed in the unaltered alloy composition at said other regions of the cast piston, said different precipitates providing strength properties suited to relatively lower service temperatures at said other regions.