Effects of Oxidation and Alumina Addition on the Physical and Mechanical Properties of Ti/Al2O3 Composites Prepared by Semi-powder Metallurgy Method

The effects of oxidation and alumina addition on the physical and mechanical properties of Ti/Al2O3 composites were studied. The variation in alumina addition used in this study was 0, 10, 20 and 30 wt%. The mixture of Ti and Al2O3 was prepared by semi-powder metallurgy method and then pressed and followed by sintering in air atmosphere at 1000 °C for 2 h. The present results show that the density of the sintered Ti/Al2O3 decreased with increasing alumina amount and oxidation. XRD and EDX analysis indicates that the sample free of alumina produced the oxides in the form of TiO2 on the surface of the composite. With alumina addition, the AlTiO2 oxide appears besides TiO2. This occurrence confirms that the oxidation of Ti increases with increasing the amounts of alumina. The intermetallic phase Ti3Al has appeared in the Ti/Al2O3 composites, which might be due to reduction in alumina by Ti. The oxidation of Ti/Al2O3 composites decreases the hardness and compressive yield strength and hardness values. The decrease in mechanical properties becomes more obvious with increasing the alumina amount which enhanced the formation of oxidation scales after sintering.