EFFECT OF TITANIUM PARTICLES ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ALUMINA MATRIX COMPOSITES

In this study, Al2O3-based composites strengthened with Ti were manufactured. High-energy milling was used to mix and grind the raw materials (450 rpm during 40 min). These powders were compacted (300 MPa) into cylindrical samples and sintered at 1500 degrees C for 2 h. Scanning electron microscopy observations show dense, fine and homogeneous microstructures, with a uniform distribution of metal particles throughout the ceramic matrix. A significant effect on the composite micro-hardness can be observed (as the titanium percentage is increased, micro-hardness is also increased). In other words, composites have a significant surface hardness, which diminishes towards the center of the piece. This attribute is highly useful for solid elements exposed to extreme strain and shearing conditions since hardness allows withstanding wear, corrosion, and friction, but the soft center allows withstanding vertical loads in the piece cross section. The fracture toughness, estimated by the indentation fracture method, showed that the manufactured composites here present higher values up to 100 % than the control sample's average (0.0 % Ti). Hence, it can be inferred that titanium particles in a ceramic matrix can disperse the energy of cracks spreading.