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通过设计准正交实验,利用极差分析法和期望方差分析法分别对Al-7Si-Mg铝合金的尺寸/因子(合金晶粒或共晶硅的尺寸与形状因子或折算因子的比值)和硬度进行分析,正交探究混合稀土添加量和固溶时效工艺的较佳工艺组合,并探讨固溶时效处理对Pr/Ce铝合金组织和性能的影响。研究的结果表明,对于合金的尺寸/因子的影响,固溶温度较大,固溶时间与时效时间其次,Pr/Ce添加量最弱。对于合金的硬度的影响,固溶温度较大,固溶时间和Pr/Ce添加量其次,时效时间最弱。综合分析得到的较佳工艺组合为:添加0.6%Pr/Ce混合稀土,在510℃固溶6 h,在180℃时效4 h。经过较佳工艺组合处理后的合金中,共晶硅相细小,平均尺寸约为10.8μm,呈雨点状分布,形状因子达到0.81,且合金硬度达到92.1 HB。
Through the design of quasi-orthogonal experiment, the size / factor of Al-7Si-Mg aluminum alloy (the ratio of the size of alloy grain or eutectic silicon to the shape factor or conversion factor) and Hardness were analyzed to study the optimum process combination of the addition of RE and the solution-aging process. The effects of solution-aging treatment on the microstructure and properties of Pr / Ce aluminum alloy were also discussed. The results show that, for the size of the alloy / factor, the solution temperature, solution time and aging time followed by the weakest Pr / Ce addition. The hardness of the alloy, the solution temperature, solution time and Pr / Ce addition, followed by the weakest aging time. The better technological combination obtained by the comprehensive analysis is as follows: adding 0.6% Pr / Ce mixed rare earth, solutionizing at 510 ℃ for 6 h and aging at 180 ℃ for 4 h. The eutectic silicon phase is fine and the average size is about 10.8μm. The shape distribution of the eutectic silicon phase is raindrop, the shape factor reaches 0.81, and the alloy hardness reaches 92.1 HB.