FRETTING WEAR OF A FINE PARTICULATE-REINFORCED ALUMINUM-ALLOY MATRIX COMPOSITE AGAINST A MEDIUM-CARBON STEEL

Particulate reinforced aluminium alloy matrix composites, produced by a powder metallurgy route, can show improved specific properties, incl uding elastic modulus and tensile and fatigue strength, over monolithi c alloys. However, these materials are difficult to join using metallu rgical processes without impinging on their mechanical performance. Me chanical fasteners or adhesives, which are normally used to join these materials, can result in fretting wear problems under vibration and f atigue regimes. The fretting wear performance of a 2124 Al-Cu-Mg alloy reinforced with 17 vol.% of 3 mu m silicon carbide particulate is com pared with an equivalent monolithic 2024 Al-Cu-Mg alloy, both in the T 4 condition, when tested against a cold-worked medium carbon steel. Du ring the early stages of fretting the composite shows significant adva ntages, reducing the degree of debris transfer to the counterface. How ever, as fretting progresses the performance of the composite becomes inferior to that of the equivalent monolithic alloy. At high numbers o f fretting cycles the degree of direct contact between the fretting fa ces is minimal and wear progresses via layers of debris. This behaviou r is interpreted in terms of the transfer and loss of debris as wear p rogresses, involving deformation-adhesion delamination, abrasion, debr is oxidation and attrition of the reinforcing particles.