Microstructure Refinement in Hypereutectic Al-Si Alloyby Compressive Torsion Processing

Abstract

The size and distribution status of second phase particles on multiphase alloys such as metal matrix composite (MMC) or hypereutectic Al-Si alloy are important factors to obtain good mechanical property of the alloys. Severe Plastic Deformation (SPD) process is capable of refining not only matrix grain but also the second phase particles and rearranging a distribution status of the particles. In the present work, Compressive Torsion Process (CTP), which was developed by the authors, was applied to refine and rearrange the second phase particles of hypereutectic Al-Si alloy. Effect of rotation number on refinement behavior was investigated. The second phase particles were successfully refined and homogeneously distributed by the CTP. The primary and eutectic silicon particles were broken into small shatters and dispersed in a matrix alloy during the CTP. The cumulative frequency of particle size was mostly identifiled under 10μm levels at the observed point close to the upper and lower dies.