【摘要】 研究了不同的铸型抽拉速率对镍基单晶高温合金 DD98的凝固参数及显微组织的影响。结果表明 ,随着抽拉速率降低 ,固 -液界面前沿的温度梯度显著提高 ,糊状区宽度减小。抽拉速率较低时 ,温度梯度在整个凝固过程中变化比较平稳。提高抽拉速率使 DD98合金由胞状凝固转变为枝状凝固 ,γ′相尺寸减小 ,并且由不规则形状逐渐变为规则的立方体形状 ,γ/γ′共晶量增加 ,共晶中的初生 γ′相尺寸逐渐减小更多还原

【Abstract】 Effects of withdrawal rate on solidification parameters and microstructure of a nickel base single crystal superalloy were investigated The results show that, with the decrease of the withdrawal rate, the temperature gradient in solid liquid interface is increased obviously and the width of mushy zone was reduced The temperature gradient is stable when the withdrawal rate is very low With the increase of the withdrawal rate, the morphology of liquid solid interface transforms from cellular to dendritic,the size of the γ′ precipitates decreases, the shape of γ′ precipitates tend to regular , the amount of γ/γ′ eutectic increases and the size of primary γ′ precipitates in γ/γ′ eutectic decreases更多还原