Effect of Modification on Microstructure and Properties of Al-17Si Alloy

Author of the article:HE Leidong， ZHONG Zhaojun， LI Pengpeng

Author's Workplace：Jiangsu Huilian Aluminum Co., Ltd., Lianyungang 222000, China

Key Words：hypereutectic Al-17%Si; metamorphism; microstructure and properties

Abstract：The microstructure of the unmodified eutectic Al-Si alloy was mainly composed of coarse primary silicon and acicular or lamellar eutectic (α+Si), which would seriously cut the matrix, and its tips and edges would cause stress concentration, which would significantly reduce the mechanical properties of the alloy, and the product can not meet the practical application requirements. The effects of different modifier treatment schemes on the microstructure and properties of hypereutectic Al-17%Si alloy were investigated. The results show that by adding 0.36% Cu-P (14%P) alloy and 0.40% rare earth lanthanum and cerium (La-Ce) to the composite modification treatment, the best refining effect, uniform microstructure refinement and optimized properties. The tensile strength increases from 126 MPa to 167 MPa without deterioration, increasing by 33% . The hardness decreases by 10% from 123 HBW to 111 HBW. The morphology of primary silicon remains the same before and after modification, and the average size of primary silicon decrease from 140 μm to 55 μm.