Effect of age-hardening on dry sliding wear behavior of mushy state rolled in-situ Al-4.5Cu-5TiB2 composites

Dry sliding wear behavior of rolling surfaces of cast in-situ Al-4.5Cu-5TiB2 composite subjected to two mushy state roll passes at the temperature for 20 vol% liquid after prior hot rolling has been investigated in their solution-treated or age-hardened conditions. The mushy state rolled composites are found to peak-age in 2 h at 170 °C after solution treatment at 495 °C. The peak-aged samples have shown greater wear resistance than that of composites with matrices in under-aged, over-aged or solution-treated condition. The wear mechanisms studied through observation of worn surfaces and wear debris by scanning electron microscopy appear to involve surface cracking. The coefficient of friction appears to be related to applied load, surface roughness and iron content of wear debris. Characterization of sample cross-sections beneath worn surfaces has shown presence of elongated grains and increased microhardness compared to that before the wear tests, confirming extensive sub-surface deformation with significant work-hardening.