Production and characterization of Al2O3, TiB2 reinforced aluminum matrix composites by hot press

In this study it was aimed to produce and characterize Al2O3-TiB2 mixture particle reinforced aluminun 4 % copper matrix composites. Utilized Al2O3-TiB2 powders were obrained in this study from TiO2, H3BO3 ve Al through combustion synthesis. It was detetrmined by XRD analyses that Al2O3and TiB2 phases were obtained by combustion synthesis. It was seen in transmission electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses that products were in the form of a few hundred micron sized hard agglomerates which were composed of TiB2 particles in a continuous Al2O3 structure . In order to separate the formed Al2O3 and TiB2 particles, and to reduce particle size, NaCl was introduced into the starting materials in %5 - %150 weight % range. It was found in SEM and partilce size analyses that the size formed particles decreased. Average particle size was 15.4 microns when %60 NaCl was added. Before introducing the Al2O3-TiB2 particles into the aluminum matrix, they were ground in alümina and WC media for size reduction.Reinforcement particles were added at %1, %3, %5 vol. % into aluminum matrix. Compozites were obtained after hot pressing at 550 oC for 30 minutes under 50 MPa pressure. It was seen in optical microscopy and SEM examinations that the reinforcement particles were dispersed homogenously in the matrix. Hardness increased in the composites as compared to unreinforced sample. Hardness of the compsite containing 1 % reinforcement that was ground in WC media was 57.7 HB10, whereas that of unreinforced sample was 50,9 HB10. Bending strength of the unreinforced sample was 433 MPa whereas the highest bending strength was attained in the composite containing 1 % reinforcement that was ground in WC media. Higher amount of reinforcement resulted in a decrease in bending strength of the composites.