研究了不同Cr、Ti、Ta含量定向凝固Ni基高温合金的1223 K恒温氧化行为。结果表明:Cr、Ti、Ta对合金的抗氧化性能在氧化的不同阶段作用各异。在氧化初期,由于Ti元素与O的亲和力很强,Ti含量高的No.3合金在氧化曲线上增重较为明显,而随着氧化的进行,Cr含量高的No.1合金增重较大,这是由于Cr的选择性氧化所致。在1223 K,No.1合金中Ti和Ta含量较低无法形成有效弥散分布于Cr2O3之中,难以形成连续的保护性氧化膜,从而不能有效地阻碍Cr3+向合金内部持续扩散。而No.2和No.3合金中Ti和Ta含量适中,形成连续膜可延缓Cr3+的持续向外扩散,对改善合金的抗氧化能力有积极作用。
Isothermal oxidation behavior of Ni-base superalloys with different Cr,Ti and Ta content at 1223 K was investigated.The results show that the different elements play a different role at different oxidation steps for oxidation resistance.In prime oxidation,the oxidation mass gain of alloy No.3 with high Ti content increases obviously due to the strong affinity between Ti and O.Following with the continuous oxidation,the mass gain of alloy No.1 with high Cr content is accelerated because of the selective oxidation of Cr.At 1223 K,the low content of Ti and Ta in alloy No.1 can not diffuse effectively in Cr2O3 to form consecutive protective oxidation scale,so that the diffusion of Cr3+ into the alloy is not be impeded.The proper content of Ti and Ta in alloy No.2 and alloy No.3 is favourable for forming the consecutive oxidation scale to postpone the diffusion of Cr3+ outward,which is a positive effect for oxidation resistance.