Effect of Cu on the Creep Behavior of Cast Al-15Si-0.5Mg Alloy

Abstract

In the present article, the effect of Cu on the microstructure and creep properties of Al-15Si-0.5Mg cast alloy was studied by using optical microscopy, scanning electron microscopy, energy dispersion spectrometry and the impression creep test. The microstructure is changed considerably in the presence of copper. The number of the Cu-rich phases increased noticeably with rising Cu content. Formation of a dendritic structure of α(Al) and modification of the eutectic Si were the other effects of increasing the Cu amount. The results showed that creep properties of the alloy increase considerably with the Cu addition. Calculating the stress exponent (n) and creep activation energy (Q) revealed that pipe diffusion climb-controlled creep is the dominant creep mechanism of the main alloy. Although Cu had no effect on the dominant creep mechanism at the lower stress, it was changed to lattice diffusion climb-controlled dislocation creep with increasing stress.