Parent bore materials of copper-containing hypereutectic Al-Si alloys have been tried with limited success. Fundamentally the reason for this technology limitation is because coppercontaining hypereutectic aluminum-silicon alloys precipitate the copper-phase late in the solidification process and hinder the feeding process to make sound castings. As a result, the copper-containing hypereutectic Al-Si alloys that have been used in the past as parent bore materials have been compromises of low silicon content, which has translated into low wear resistances and the need for special surface treatments. This paper presents the new advancements to the old hypereutectic aluminum-silicon technology for linerless parent bore aluminum blocks. The technology is centered around the use of a copper-free hypereutectic aluminum-silicon alloy parent bore material and a piston coating that has particles of a solid lubricant embedded in the plated coating. Because there are no commercially available copper-free hypereutectic aluminum-silicon alloys, this paper contains the thermal/physical/mechanical data for such alloys.

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