Hf在粉末冶金镍基高温合金中的相间分配及对析出相的影响

利用三维原子探针（3DAP）,SEM,TEM和相分离方法,研究了5种Hf含量的FGH97粉末冶金高温合金中Hf在γ基体、γ′相和MC相中的分配,以及Hf对γ′和MC析出相的数量、组成和形貌的影响.结果表明:Hf主要进入γ′相和MC型碳化物,γ′相变为（Ni,Co）₃（Al,Ti,Nb,Hf）,MC碳化物变为（Nb,Ti,Hf）C.随着合金中Hf含量的增加,Hf进入γ′相的比例基本不变,进入MC相的比例逐渐增大,进入γ相的比例逐渐减小,即Hf在γ′和MC相的分配比R₁逐渐减小,在γ′和γ相的分配比R₂逐渐增大,R₁和R₂的平均值分别为1:0.1和1:0.05,这表明Hf主要分配在γ′相中,其次分配在MC相中.Hf促进γ′相和MC相析出,影响γ′相的尺寸和形貌,对MC碳化物的尺寸和形貌的影响并不明显.

PARTITION OF Hf AMONG THE PHASES AND ITS EFFECTS ON PRECIPITATES IN PM Ni-BASED SUPERALLOY FGH97

The partition behavior of hafnium among different phases in FGH97 PM(powder metallurgy) superalloy and its effects on the precipitation behaviors of MC carbide and 7’ phase were studied by means of 3DAP,SEM,TEM and physiochemical phase analysis.The results showed that element Hf mainly exists in 7’ phase and MC carbide,which makes 7’ composition transform to(Ni, Co)3(Al,Ti,Nb,Hf),also makes MC transform to(Nb,Ti,Hf)C.With Hf addition increasing,the proportion of Hf in 7’ maintains constant,but in MC carbide increases and in 7 decreases,which means that partition ratio(R\) between 7’ phase and MC carbide is decreased,while partition ratio {R2) between 7’ phase and 7 matrix is increased,the average partition ratio between 7’ phase and MC carbide is about 1:0.1,and the average partition ratio between 7’ phase and 7 matrix is about 1 ’. 0.05.Hf is helpful to the precipitations of 7’ phase and MC carbide,the morphology and size of 7’ phase are influenced more by Hf than these of MC carbide.