新型细化剂对K4169高温合金微观组织的影响

研究了新型晶粒细化剂对K4169高温合金枝晶组织、元素显微偏析和合金相的影响。实验结果表明：在同一浇注温度下，细晶铸造试样的一次枝晶主轴长度较普通铸造试样明显缩短，但二者的二次枝晶臂距没有显著差别。晶粒细化后，晶粒的形态由普通铸造组织中的树枝晶向细晶组织中的粒状晶转变，而反合金中主要元素Fe、Cr、Nb、Mo和Ti的偏析减轻，这些均有利于提高细晶铸件的机械性能。另外，MC型碳化物和Laves相的尺寸、数量和形貌在晶粒细化前后变化不大。

Effects of New Refiners on Microstructures of Cast Superalloy K4169

In this paper, effects of new grain refiners on dendrite structures, microsegregation and precipitated phases of cast superalloy K4169 have been studied. The results show that at the same casting condition, the average principal axis length of the primary dendrites has been shortened with the addition of the refiner. However, the secondary dendrite arm spacing keeps almost unchanged. Additionally, the grain morphology has been transformed from dendrite in conventional castings to granulation in fine grained castings and the segregation ratios of main alloy elements mitigate with the decrease of grain size, which are beneficial for the improvement of mechanical properties. Meanwhile, it is found that there is no remarkable change in the size, amount and morphologies of MC type carbides and Laves phase after grain refinement.