Fe含量对AlSiCuMg合金中富Fe相与缩松的影响

Effects of Fe Content on Fe-rich Intermetallics and Porosity in AiSiCuMg Alloys

根据AlSiCuMg合金的实际应用,设计了不同Fe含量的试样。利用试验分析结合热力学计算,研究了Fe含量变化对富Fe相种类、数量以及最大尺寸的影响。结果表明,Fe含量增会促进合金中β-Fe相的析出与长大,并使π-Fe相的形貌由简单的汉字状转化为较复杂的骨骼状。另外,将Fe含量控制在一定范围内可以抑制β-Fe相析出。通过试验和理论分析研究了β-Fe相对缩松形成与长大的影响机制,结果发现,针片状的β-Fe相在结晶前沿阻断了枝晶间补缩,导致缩松产生。此外,由于富Fe相比α-Al的气-固相界面能更低,促使氢在富Fe相表面优先析出,将进一步扩大缩松体积。从拉伸结果可以看出,Fe对合金的综合性能影响较大,当Fe含量超过0.25%,合金趋向脆性断裂。

According to the application of Al-Si-Cu-Mg alloy,experimental samples with different Fe contents were designed.The influence of Fe content on the type,amount and maximum size of Fe-rich phase was investigated by experimental and thermodynamic analysis.The results indicate that the increase of Fe content promotes the precipitation and growth of β-Fe phase,and make the morphology of π-Fe phase transformed from a simple Chinese character to a complex skeleton.The precipitation of β-Fe phase can be inhibited by controlling Fe content within a range.In addition,the mechanism of β-Fe on porosity formation and growth was analyzed through theoretical and experimental analysis.The results reveal that the needle-shaped β-Fe phases inhibit interdendritic channels and leads to the formation of porosity.Furthermore,due to the lower gas-solid interface energy of Fe-rich phase,hydrogen is preferentially precipitated on Fe-rich phase surface,which further enlarges the porosity volume.Based on tensile results,Fe has great effects to the mechanical properties of the alloy.When Fe content exceeds 0.25%,the alloy tends to brittle fracture.