中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 29 No. 8 August 2019 |
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China;
3. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, China;
4. Fujian Xiangxin Shares Co., Ltd., Fuzhou 350000, China）
Abstract:The microstructural evolution and mechanical properties of Al-18Si-4Cu-0.5Mg alloy modified by the addition of La-Ce rare earth elements through OM, SEM, EPMA and tensile tests were investigated. The results of OM and SEM analyses indicated that primary Si particles were significantly refined from coarse block-like and irregular polygonal shapes into fine flaky shapes, while eutectic Si particles were modified from coarse and needle-like into fine and rod- or coral-like shapes with increase of La-Ce addition. The alloy exhibited the minimum primary Si particle size and the best mechanical properties with the addition of 0.3 wt.% La-Ce. The average particle size decreased from 61 to 28 μm, the ultimate tensile strength increased from 222 to 242 MPa and the elongation increased from 3.2% to 6.3%. In addition, modification mechanisms and fracture modes were explored by the means of SEM and EPMA.
Key words: Al-18Si-4Cu-0.5Mg alloy; primary Si; eutectic Si; La-Ce addition; mechanical properties
