Wear properties of high-pressure die cast and thixoformed aluminium alloys for connecting rod applications in compressors

Hypereutectic AI-Si casting alloys are attractive candidates for connecting rod applications in compressors. Several hypo- and hypereutectic Al-Si alloys were produced by high-pressure die casting and thixoforming in the present work. Hypereutectic Al-Si alloys wear less than the near-eutectic and hypoeurectic alloys under the severe wear conditions encountered in compressors, confirming the impact of Si on wear resistance. Cu also improves wear properties. The thixoformed alloys wear at comparable rates with high-pressure die cast alloys at lower Si levels, implying that the lower Si content of the former is compensated for by the thixoforming processing route. Hypereutectic compositions, uniform dispersion of fine Si particles and thixoforming as the production route are all good for a superior wear performance. The substantial hardening produced by the T6 heat treatment, however, does not translate into a sizable improvement in wear resistance of the thixoformed alloys. (C) 2007 Elsevier B.V. All rights reserved.