Mg含量对Al-xMg-1Si合金热裂敏感性的影响

Effect of Mg content on hot tearing susceptibility of Al-xMg-1Si alloys

为了揭示Mg含量变化对铝合金热裂敏感性的影响,计算了Al-x Mg-1Si合金的热裂敏感性参数,测试了合金凝固路径、枝晶相干温度和凝固区间温度等参数,并对合金热裂区域的显微组织及断口形貌进行了分析.结果表明,合金热裂敏感性随着Mg含量的增大而减小.α-初生相的枝晶干涉温度及析出温度随Mg含量的增加而降低,Mg_(2)Si相的析出量及析出温度随Mg含量的增大而提高.随着Mg含量的增加,凝固后期晶界上共晶成分残余液相增加,Mg 2Si相凝固潜热增加,Mg_(2)Si析出对晶界的钉扎作用增强,因而合金热裂敏感性降低.

In order to reveal the influence of Mg content variation on the hot tearing susceptibility(HTS)of aluminimum alloy,the thermal crack sensitivity coefficients(CSC)of Al-x Mg-1Si alloys were calculated,and related parameters,e.g.alloy solidification path,dendrite coherent temperature and solidification interval temperature,were tested.The microstructure and fracture morphology in the hot tearing area of alloys were analyzed.The results show that the HTS of alloys decreases with the increasing Mg content.The dendrite interference temperature and precipitation temperature ofα-Al primary phase decrease with the increase of Mg content,while the precipitation quantity and precipitation temperature of Mg_(2)Si phase increase with the increasing Mg content.With the increase of Mg content,the residual liquid phase with eutectic composition on grain boundaries increases,the solidification latent heat of Mg_(2)Si phase increases,the pinning effect of Mg_(2)Si precipitated on the grain boundaries increases,so the HTS of alloys decreases accordingly.