(1. 长安大学 材料科学与工程学院，西安 710064；
2. 西安赛特思迈钛业有限公司，西安 710018；
3. 西北工业大学 凝固技术国家重点实验室，西安 710072)
摘 要: 基于实验研究、热力学计算与动力学分析，研究了Ni含量对Co-Al-W基单晶高温合金凝固特性的影响。结果表明：无Ni和添加Ni的Co基单晶高温合金均具有典型的枝晶组织，但Ni的添加增大了合金的一次枝晶间距。同时，Ni的添加增大了Al和W元素的显微偏析倾向，降低了Ta元素的显微偏析倾向，但对Ti元素的显微偏析倾向的影响较小。无Ni合金的枝晶间析出相为初生γ′相和(β+γ′)共晶相，而含Ni合金的枝晶间析出相为初生γ′相，即Ni的添加改变了合金的凝固路径与铸态组织。同时，Ni的添加对Co-Al-W基单晶高温合金凝固特征温度的影响不明显。
关键字: Ni添加量；Co-Al-W基单晶高温合金；枝晶组织；显微偏析；凝固路径；凝固特征温度
（1. School of Materials Science and Engineering, Chang’an University, Xi’an 710064, China;
2. Xi’an SaiteSimai Titanium Industry Co., Ltd., Xi’an 710018, China;
3. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:The effect of Ni addition on solidification characteristics of Co-Al-W based single crystal superalloy was investigated via experimental, thermodynamical and dynamical analysis. Both Ni-free and adding Ni Co-Al-W based single crystal superalloy has the typical dendritic microstructure, and Ni addition increases the primary dendritic arm spacing of single crystal superalloy. Meanwhile, with increasing Ni content, the microsegregation degrees of Al and W elements increase, the microsegregation degree of Ta element decreases, while Ni addition has little influence on the microsegregation degree of Ti element. Moreover, the interdendritic precipitations of Ni-free single crystal superalloy are primary γ′ phase and (β+γ′) eutectic phase, while the interdendritic precipitation of Ni single crystal superalloy is primary γ′ phase, which indicates that Ni addition changes the solidification path and as-cast microstructure of single crystal superalloy. In addition, the influence of Ni addition on solidification characteristic temperatures of Co-Al-W based single crystal superalloy is not obvious.
Key words: Ni addition amount; Co-Al-W based single crystal superalloy; dendritic microstructure; microsegregation behavior; solidification path; solidification characteristic temperatures
