Creep properties of an Al-2024 composite reinforced with SiC particulates

Creep tests were conducted on an Al-2024 alloy reinforced with 15% SiC particulates. In this composite, as in earlier experiments on the unreinforced Al-2024 alloy, there is a continuous precipitation of fine particles throughout the tests. The creep behaviour of the composite reveals the presence of a threshold stress, and this stress depends upon both temperature and applied stress because more copious precipitation occurs in the more time-consuming tests conducted at the lower stress levels. The results for the composite are analysed using a procedure similar to that developed earlier for the unreinforced alloy. It is shown that the rate-controlling deformation mechanism is dislocation climb within the matrix alloy with a stress exponent of about 4.4 and an activation energy equal to that anticipated for lattice self-diffusion in pure aluminium.