Influence of heat treatment on the coefficient of thermal expansion of Al (6061) based hybrid composites

This paper describes study of coefficient of thermal expansion (CTE) of as-cast and heat-treated aluminium 6061 based hybrid composites, reinforced with SiC particulate and E-glass fiber. These hybrid composites were subjected to different aging durations. The liquid melt technique route was used to produce the castings. Castings were machined in accordance with ASTM standard followed by the heat-treatment process. All the specimens were aged to different periods 1 h, 3 h, 5 h, and 7 h at an aging temperature of 175 degrees C. CTE tests were performed on the different composites in the both as-cast and heat-treated conditions. In each case the CTE of the composites were found to increase with increase in aging durations. Solution heat treatment at 530 degrees C followed by artificial aging at 175 degrees C was found to increase in dimension change of every specimen tested. The CTE curves exhibited some residual strain, which were decreased with the increase in the aging durations. An attempt is made in the paper to explain these phenomenon. (c) 2006 Elsevier B.V. All rights reserved.