فهرست نشریات علمی دسترسی آزاد ایران

The present study investigates the mechanical and tribological behaviour of Al alloys and Al/ZrO₂ ex-situ composites, focusing on their microstructural evolution and property enhancement. Al/ZrO₂ composites were synthesised using stir casting, incorporating 1, 3, and 5 wt.% ZrO₂ particles. Alloys and composites were characterizedusing X-ray diffraction (XRD), optical microscope (OM), and scanning electron microscopy (SEM)to analyse phase formation, particle distribution. Microstructural analysis revealed homogeneous dispersion of ZrO₂ particles, promoting load transfer and matrix strengthening. Mechanical properties were analysed using Vickers microhardness and uniaxial tensile tests, demonstrating substantial increases in hardness and tensile strength with increasing ZrO₂ content due to grain refinement, dislocation strengthening, and Orowan strengthening mechanisms. Tribological performance was evaluated using a pin-on-disc apparatus under varying loads (10N- 30N) and sliding speeds (1 m/sec -3 m/sec). The Al/ZrO₂ composites exhibited a significant reduction in the wear (up to 50%) compared to the unreinforced alloy, attributed to the load-bearing capacity of ZrO₂ particles and the formation of a protective tribolayer. Surface morphology of the worn samples, analysed using SEM, indicated a transition from abrasive to mild adhesive wear with the addition of ZrO₂. Further topographical parameters were studied using atomic force microscopy (AFM), which suggests a decrease in surface roughness from 0.87 µm to 0.70 µm at3wt. % of ZrO2 compared to the base alloy.