挤压铸造Al-9.5Si-0.45Mg-_(x)Cu合金组织和性能的演变

Evolution of Microstructure and Properties of Squeezing Casting Al-9.5Si-0.45Mg-_(x)Cu Alloy

通过模拟计算、扫描电镜、X射线衍射、力学性能测试以及透射电镜等方法分析了Cu含量对挤压铸造Al-Si-Mg_(2)-Cu合金组织和性能的影响。结果表明:铸态下,随着Cu含量的增加,Mg_(2)Si相不断减少,Q相和θ相不断增多;Cu达到0.5wt.%时,Mg_(2)Si相消失,Q相析出达到最大值,继续增加Cu,仅θ相不断增多并且有粗化的趋势。T6态下,随着Cu含量的增加,屈服强度不断提升,伸长率不断下降。但Cu在0.5wt.%以下时,强度上升不明显,伸长率略有下降;超过0.5wt.%,强度明显上升,伸长率急剧下降,且断裂模式有从韧性断裂往解理断裂转变的趋势。

The effects of Cu contents on the microstructures and properties of squeezing casting Al-Si-Mg_(2)-Cu alloys were analyzed by means of simulation calculation,scanning electron microscopy,X-ray diffraction,mechanical property testing and transmission electron microscopy,and so on.The results show that in ascast state,with the increase of Cu content,the Mg_(2)Si phase decreases,the Q phase and theθphase increase continuously.When the content of Cu reaches 0.5wt.%,the Mg_(2)Si phase disappears,the Q phase reaches maximum dose,and only theθphase increases and has a tendency to coarsen.In the T6 state,with the increase of Cu content,the yield strength increases and the elongation decreases continuously.However,when the content of Cu is below 0.5wt.%,the strength does not increase signi?cantly,and the elongation decreases slightly;when it exceeds 0.5wt.%,the strength increases signi?cantly,and the elongation decreases sharply,and the fracture mode has a trend of transforming from ductile fracture into cleavage fracture.