Improving mechanical property and corrosion resistance of high electrical conductivity Al-Ce-Sc-Y and Al-Mg-Si-Ce-Sc-Y alloys by laser shock peening

Abstract

The high electrical conductivity Al-Ce-Sc-Y and Al-Mg-Si-Ce-Sc-Y alloys were used to study the effects of laser shock peening on their mechanical property, pitting and intergranular corrosion resistance. The strength and elongation of the alloys were improved simultaneously at the expense of very low electrical conductivity after laser shock peening due to the gradient structure and residual compressive stress. After two side laser shock peening, the strength and elongation of Al-Ce-Sc-Y and Al-Mg-Si-Ce-Sc-Y alloys increased to 231 ± 3 MPa/16.2 ± 0.2 % and 359 ± 3 MPa/17.1 ± 0.3 %, respectively. The samples with two surface states were used to study the corrosion behaviors. The number and depth of corrosion pits can be significantly reduced by laser shock peening and the crystallographic corrosion morphology exists in the corrosion pits. After two side laser shock peening with polished surface, the intergranular corrosion depth of Al-Mg-Si-Ce-Sc-Y alloy can reach the minimum and the intergranular corrosion cracks are much finer at the same depth. The Al-Ce-Sc-Y alloy had no tendency of intergranular corrosion, but the unpolished surface was prone to form the deep corrosion pits rather than occurred uniform corrosion. According to the microstructure analysis, the corrosion mechanism of pitting and intergranular corrosion was revealed.