Electric field modification during superplastic deformation of 15 vol% SiCp/LY12 Al composite

摘要

Silicon carbide particulate-reinforced aluminium (SiCp-Al) composites possess a unique combinationof high specific strength, high elastic modulus, good wear resistance and good thermal stability,which makes them attractive as metal matrix composites (MMCs). Some work focusing on thesuperplasticity of SiC particulate reinforced composites has been conducted in order to improve theformability. The study of superplastic deformation in the presence of an external electric field is arelatively new development but to the authors' best knowledge, has not yet been reported for MMCs.In this paper, 15 vol%} SiCp/LYl2 Al composite was fabricated by spray atomization and co-deposition and pre-treated by isothermal hot compression as well as isothermal hot forward extrusion(extrusion ratio: 10.0). The superplastic deformation behaviour of the 15 vol%) SiCp/LY12 Alcomposite under an external electric field has been investigated. The electroplastic effect of 15 vol%SiCp/LYl2 Al composite and the influence of deformation process parameters on the superplasticityhave also been studied. The experimental results show that: (i) the optimum intensity of theelectric field improves the superplasticity of 15 vol% SiCp/LYl2 Al composite, i.e. the strain-ratesensitivity index (m) is increased by 13% and the elongation (δ) is 420%, being increased by 20%;(ii)the optimum intensity of the electric field decreases the flow stress by 16% during the superplasticdeformation of 15 vol% SiCp/LY 12 Al composite; (iii) the optimum intensity of the electric fieldmakes the grain size finer during the superplastic deformation of 15 vol% SiCp/LYl2 Al composite,which provides te microstructural conditions for the improvement of superplasticity, but the electricfield has only a slight influence on the microstructure before superplastic deformation.