固溶温度对新型Al-12.7Si-0.7Mg合金挤压材组织性能的影响

针对我国自主研制的新型Al-12.7Si-0.7Mg合金挤压型材,采用金相显微镜、扫描电镜及其附带的能谱分析仪以及拉伸实验研究了固溶温度对铝基体晶粒、合金相粒子尺寸、形状及数量以及挤压材力学性能的影响规律,结果表明:Al-12.7Si-0.7Mg合金挤压材基体中存在大量尺寸极其细小的点状Mg2Si相及大量微米级共晶Si粒子和少量微米级AlFeSi过剩结晶相;固溶温度从440℃升高至540℃,尺寸极其细小的点状Mg2Si相逐渐回溶入基体消失,微米级共晶Si颗粒及含AlFeSi的过剩结晶相粒子形状趋于球化,而铝基体晶粒呈现出略有长大的趋势,且共晶硅颗粒具有较明显的细化铝基体晶粒的作用;合金挤压材的强度及延伸率随固溶温度升高分别呈现出单调增大及总体下降的趋势;新型Al-12.7Si-0.7Mg合金挤压材比较适宜的固溶温度为520℃,合金挤压材经最佳固溶温度固溶水淬再经170℃×2.5 h时效处理后的Rp0.2≥279 MPa,Rm≥330 MPa,A≥9.9%。

Effect of Solution Temperature on Microstructure and Properties of Al-12.7Si-0.7Mg Aluminum Alloy Extrusion

The effect of the solution temperature on the aluminum matrix grains,the size,shape and number of the second-phases particles,and the mechanical properties of the self-developed new type Al-12.7Si-0.7Mg extrusion were investigated by means of OM,SEM/EDS and tensile test.The results showed that there were many ultra-fine dot-like Mg2Si particles,a large number of micro-sized eutectic silicon particles and small amounts of AlFeSi-containing constituent.The ultra-fine dot-like Mg2Si particles gradually dissolved into matrix,and the micron eutectic silicon and the AlFeSi-containing constituent particles were spheroidized,but the aluminum grains grew as the solution temperature elevated from 440 to 540 ℃,remarkably,the eutectic silicon particles had the effect of refined the aluminum matrix grains.The strength of the Al-12.7Si-0.7Mg alloy was monotonously increased but the elongation of the alloy was overall decreased as the solution temperature elevated.The optimum solution temperature of the Al-12.7Si-0.7Mg alloy was 520 ℃,and the yield strength,the tensile strength and the elongation of the Al-12.7Si-0.7Mg alloy was more than 279,330 MPa and 9.9%,respectively,when the alloy was solutionized at 520 ℃ and then aged at 170 ℃ for 2.5 h.