Development of Al–Si–Mg alloys reinforced with diboride particles

Abstract

A series of aluminium composites, with varying volume fractions of diboride particles, were made by mixing various proportions of aluminium alloy and titanium diboride (TiB 2) powders followed by hot extrusion. Different studies were carried out in the composites developed in order to obtain their general properties. The possible reaction between the matrix and reinforcement was evaluated by performing heat treatments regarding temperature at a fixed time of 1 h and at different temperatures of 350, 400, 450 and 500 °C. In this study, optical and scanning electron microscopy (SEM) with X-ray microanalysis, were used to determine the growth of the reaction layer. Mechanical properties such as ultimate strength and strain to failure were studied. The tests were performed at room and high temperature in the material in state T1 and T6. The type of damage was analysed by SEM. Tribological properties were analysed in conditions of dry friction as well as lubrication with standard lubricant in automotive industry of the type SAE 250. The evolution of the coefficient of friction in front of the speed of sliding, applied pressure, regime of lubrication and content of reinforcement in the composites was studied. The contribution also describes results from corrosion tests on aluminium composites with different percentages of reinforcement. Specimens were examined after exposure to the corrosive solution employing SEM and the type and amount of corrosion was observed.