Microstructure, hardness and thermal properties of Al4.5Cu/TiO2 composites produced by mechanical alloying

Al4.5Cu/TiO2 composites were fabricated from their elemental powders by the mechanical alloying method. Microstructural and thermal properties of the composites were investigated by a combination of differential thermal anal sis (DTA), scanning electron microscopy with energy dispersive X-ray detection (SEM-EDX), and X-ray diffraction (XRD). Microstructural evolutions, phase transformations, and crystallite size changes were investigated depending on the milling time. XRD and SEM results showed that there were a more homogeneous structure and shrinkage in grain size due to the increased milling time. The DTA results showed an endothermic peak of around 650 degrees C which indicates the melting temperature of Al. Besides, the mechanical properties of the pressed and sintered composites were investigated by Vickers micro-hardness testing. The results showed that microhardness values significantly increased as milling time increased from 5h to 10h. The maximum microhardness value of 173 +/- 10 HV was obtained for Al4.5Cu with 20 wt% TiO2 composite after milling for 10h.