深冷处理对压铸铝硅合金力学性能与微观组织的影响

Effect of Cryogenic Treatment on the Mechanical Properties and Microstructure of Die Casting Al-Si Alloys

借助Image-Pro Plus辅助分析,采用光学显微镜(OM)、扫描电子显微镜(SEM)、电子背散射(EBSD)等手段,研究了深冷处理对压铸铝硅合金微观组织和力学性能的影响。结果表明:深冷处理可以有效提升压铸铝硅合金的力学性能。随着深冷时间的延长,深冷处理对合金力学性能的提升作用为先增加后减小的变化规律。与铸态合金相比,经12 h深冷处理后合金的力学性能获得最大的提升,抗拉强度为213.2 MPa,提升了15.4%,伸长率为8.65%,提升了36.2%,硬度HV为106.6,提升了18.1%。继续延长深冷时间,α-Al相、共晶Si相等开始缓慢长大,导致力学性能有所下降。深冷处理可以有效细化合金的α-Al相,改善共晶Si相和含铁相的尺寸和形貌,起到了细化组织和位错强化的作用。

The effect of cryogenic treatment on the mechanical properties and microstructure of die casting Al-Si alloys was investigated using optical microscopy(OM),scanning electron microscopy(SEM)and tensile testing with the aid of Image-Pro Plus-assisted analysis.The results showed that the cryogenic treatment could effectively improve the mechanical properties of the die casting Al-Si alloys.With the extension of cryogenic time,the degree of enhancement of the mechanical properties of the alloy by the cryogenic treatment showed an increasing and then decreasing pattern of change.Compared to the as-cast alloy,when the cryogenic time was 12 h,the tensile strength of the alloy was 213.2 MPa increased by 15.4%,the elongation was 8.65%increased by 36.2%,and the hardness was HV 106.6 increased by 18.1%.At this time,the mechanical properties of the alloy reached the best.Continue to extend the deep cold time,α-Al phase and eutectic Si phase began to grow slowly,which led to the decline of the mechanical properties.The cryogenic treatment can effectively refine theα-Al phase of the alloy,improve the size and morphology of the eutectic Si and Fe-containing phases,and play a role in refining the microstructure and dislocation strengthening.