将900 ℃常氧分压(900-PreO)、950 ℃常氧分压(950-PreO)和1000 ℃低氧分压(1000-LPreO)预氧化应用于Co-Al-W基高温合金，研究其高温氧化和热腐蚀行为，利用XRD、SEM和EDS表征了合金氧化层的结构和形貌特征。结果表明，采用900-PreO、950-PreO和1000-LpreO均可获得结构致密的预氧化层。1000 ℃氧化时，900-PreO预氧化层中的Cr₂O₃层进一步氧化而减薄，削弱了其对O及金属元素扩散的阻碍，致使氧化增重与未预氧化合金的情况相近；1000-LPreO预氧化生成的TiTaO₄层易开裂，导致氧化层脱落严重，抗氧化性能较差；而950-PreO预氧化生成的CoCr₂O₄和Al₂O₃层致密且连续，氧化层的保护性强，氧化增重减缓。Co-Al-W基高温合金的热腐蚀中，950-PreO预氧化层中的CoWO₄和Al₂O₃层阻止腐蚀介质进入合金基体，腐蚀增重锐减超过了80%。

In 2006, stable γ' phase was found in Co-Al-W alloy, which provides a new way for developing Co-based superalloys. In order to meet the requirements for applications, the Co-Al-W-based superalloys need to have good oxidation and corrosion resistance. But the oxidation and corrosion resistance of the Co-Al-W-based superalloys is relatively low. In this work, pre-oxidation treatments were used to improve the oxidation and corrosion resistance. Three types of pre-oxidation treatments were carried out at 900 ℃ (in air), 950 ℃ (in air) and 1000 ℃ (in 1%O₂+99%Ar), which were marked as 900-PreO, 950-PreO and 1000-LPreO, respectively. High temperature oxidation tests of both the pre-oxidation treated and untreated superalloys were carried out at 1000 ℃. And hot corrosion behaviors were also investigated at both 800 and 850 ℃. XRD, SEM and EDS were used to examine the characteristics of the oxidation and corrosion behaviors. The results show that the pre-oxide layers of the superalloys after different pre-oxidation treatments are compact. During oxidation at 1000 ℃, the Cr₂O₃ scale in 900-PreO treated superalloy is oxidized to form volatile products, and the diffusion resistance of both oxygen and the metal elements through the oxide layer is poor. In 1000-LPreO treated superalloy, serious spallation of the oxides occurs and leads to poor oxidation resistance. In 950-PreO treated superalloy, since the continuous CoCr₂O₄ and Al₂O₃ scales help to reduce the diffusion of oxygen and the metal elements, the mass gain of 950-PreO treated superalloy is consequently decreased. During the hot corrosion process, the pre-oxide layer of 950-PreO treated superalloy can hinder the diffusion of corrosive medium. Therefore, the corrosion resistance can be significantly improved by 950-PreO treatment, and the mass gain is decreased by over 80%.