【摘要】 为了进一步降低合金凝固偏析程度和优化真空自耗冶炼（VAR）工艺，利用液态金属冷却法（LMC）对GH4151合金进行定向凝固实验，采用光学显微镜、扫描电镜及电子探针等研究了冷却速率对GH4151合金定向凝固组织及元素偏析的影响。结果表明：随着冷却速率的增加，一次枝晶间距λ₁及二次枝晶间距λ₂均逐渐减小，两者与冷却速率间满足相似的函数关系。而且，枝晶干及枝晶间γ′相尺寸也随冷却速率的增加逐渐减小，组织均匀性提高。对凝固组织元素成分分布的电子探针分析表明：GH4151合金主要偏析元素为W、Nb、Ti,偏离程度在20%以上，且3种元素显微偏析程度均随冷却速率的增加而加重，原因在于随着冷却速率增加，凝固前沿固相层可供溶质扩散的时间减少，扩散效果减弱。更多还原

【Abstract】 In order to further reduce the degree of alloy solidification segregation and optimize the vacuum consumable smelting（VAR） process, directional solidification experiments were conducted on GH4151 superalloy using liquid metal cooling（LMC） method. The effect of cooling rate on directional solidification structure and element segregation of the GH4151 superalloy was studied means of optical microscope, scanning electron microscopy and electron probe microanalysis. The results show that as the cooling rate increases, the primary dendrite spacing λ₁ and secondary dendrite spacing λ₂ both gradually decrease, and the relationship between them and the cooling rate is similar. Moreover, the γ′ phase size between dendrite arm and interdendritic decreases gradually with the increase of cooling rate, and the uniformity of the microstructure improves. The electron probe microanalysis of the elemental composition distribution in the solidification structure shows that the main segregation elements of the GH4151 superalloy are W, Nb and Ti, with a deviation degree of more than 20%. The microsegregation degree of all three elements increases with the increase of cooling rate, because as the cooling rate increases, the time available for solute diffusion in the solidified front solid layer decreases, and the diffusion effect weakens.更多还原