摘要
在重力铸造条件下制备了不同Cu含量(4%~6%,质量分数,下同)Al-Cu-Mg-Sc合金,采用500℃×4 h+520℃×6 h的双级固溶,水冷后进行175℃×5 h时效。通过维氏硬度测试、室温拉伸性能测试试验、扫描电镜分析(SEM)等手段,研究了不同Cu含量对试验合金显微组织和力学性能的影响,进而优化Al-Cu-Mg-Sc铝合金成分。结果表明,经热处理后,随Cu含量从4.26%提高至5.58%,Al_(2)Cu析出相含量持续提高,热处理后合金屈服强度从191 MPa提升至216 MPa,抗拉强度从323 MPa提升至355 MPa,伸长率维持在13%附近。然而,当Cu含量较高时(6.13%),微观组织中Al_(2)Cu相体积分数较高,固溶后进入基体的Al_(2)Cu相数目有限,有大量Al_(2)Cu相残留在晶界处,经过时效处理后,合金的强化效果不能随Cu含量的增加而继续提升。因此整体上,随Cu含量提高,时效态高Cu含量合金的硬度和抗拉强度先增加随后趋于平稳,断后伸长率呈现先增加后降低的规律。Cu含量为5.58%的铸造Al-Cu-Mg-Sc铝合金时效后获得最佳综合性能,其硬度为117 HV,抗拉强度和屈服强度分别为355 MPa、216 MPa,断后伸长率为13.5%。
Al-Cu-Mg-Sc alloy with different Cu contents(4%-6%, mass fraction, similarly hereinafter) was prepared by gravity die casting process, and a two-stage solution treatment(500 ℃×4 h+520 ℃×6 h) with water cooling was carried out, subsequently aged at 175 ℃ for 5 h.Effect of Cu content on microstructure and mechanical properties of the tested alloy was investigated by means of Vickers hardness test, room temperature tensile test, scan electron microscope observation. Then, the optimized composition of Al-Cu-Mg-Sc alloy was obtained. The results show that when the Cu content increases from 4.26% to 5.58%, the precipitation content of Al_(2)Cu phase increases continuously after heat treatment, and the yield strength and tensile strength of the alloy increase from 191 MPa and 323 MPa to 216 MPa and 355 MPa, respectively, and the elongation is maintained around 13%. While the Cu content is higher(6.13%), the volume fraction of Al_(2)Cu phase in the microstructure is relatively high, and the amount of Al_(2)Cu phases dissolved into the matrix after solution treatment is limited, and a large amount of residual Al_(2)Cu phases remain at the grain boundary. After aging, the strengthening effect of the high-Cu alloy cannot continue to increase as the Cu content increases. Therefore, on the whole, with the increase of Cu content, the hardness and tensile strength of the alloys with high Cu content increase firstly and then stabilize, the elongation of the alloys first increases and then decreases. The cast Al-Cu-Mg-Sc alloy with Cu content of 5.58% after aging can achieve the best overall properties, of which the hardness is 117 HV, tensile strength and yield strength are 355 MPa and 216 MPa, respectively, and the elongation is maintained in 13.5%.
作者
郑元凯
李龙飞
金康
李春明
张文良
梁君宁
Zheng Yuankai;Li Longfei;Jin Kang;Li Chunming;Zhang Wenliang;Liang Junning(Beijing Research Institute of Mechanical and Electrical Technology Ltd.,Beijing 100083,China;Beijing National Innovation Institute of Lightweight Ltd.,Beijing 100083,China;China Machinery Industry Technology Research Institute of Precision Forming,Wuhu Anhui 241000,China;Hebei Fengwei Machinery Co.,Ltd.,Xingtai Hebei 054500,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2022年第5期53-58,共6页
Heat Treatment of Metals
基金
先进成形技术与装备国家重点实验室开放课题(SKL2020006)。
