凝固压差对真空差压铸造ZL114A合金微观组织及高温蠕变性能的影响

Effect of solidification pressure differences on microstructure and high temperature creep properties of vacuum counter-pressure casting ZL114A alloy

采用真空差压铸造技术在不同凝固压差下制备ZL114A合金试样,通过金相、扫描电镜、高温蠕变性能测试等技术考察凝固压差对真空差压铸造ZL114A合金初生相组织、共晶硅形貌和高温蠕变性能的影响。结果表明:随着凝固压差的增大,合金的初生相组织得到明显细化,由粗大的树枝晶转变为细小的等轴晶,共晶硅形貌也由粗大的针状向短棒或颗粒状转变;同时ZL114A合金的高温蠕变性能得到显著改善;当凝固压差为90 kPa时,其蠕变时间达到100 h后合金试样仍未见断裂,此时试样的变形量仅为0.21%。

ZL114A alloy samples were prepared by vacuum counter-pressure casting technique under different solidification pressure differences.The effects of solidification pressure difference on the primary phase structure,eutectic silicon morphology and high temperature creep properties of vacuum counter-pressure casting ZL114A alloy were investigated by metallography,SEM and high temperature creep performance tests.The results show that as the solidification pressure difference increases,the primary phase structure of the alloy is remarkably refined from coarse dendrites to fine equiaxed crystals,and the eutectic silicon is also transformed from a coarse needle shape to a small short rod or granular shape.At the same time,the high temperature creep property of ZL114A alloy is significantly improved.When the solidification pressure difference is 90 kPa,the alloy sample still has no fracture after the creep time reaches 100 h.At this time,the deformation of the sample is only 0.21%.