The effect of use of as PCA(process control agent) to prevent the carbon contamination during mechanical alloying process and the precipitation behavior in Ni-20Cr-20Fe-5Nb bulk alloy after aging were investigated. NbC and were formed during mechanical alloying and consolidation processes in the Ni-20Cr-20Fe-5Nb alloy in which methanol() was added as PCA. Formation of NbC in this alloy decreased the amount of Nb dissolved in the Ni matrix. The use of as PCA in Ni-20Cr-20Fe-5Nb alloy prevented the formation of NbC and increased the hardness. The increase of hardness in this alloy was attributed to the increased amount of Nb dissolved in the Ni matrix. After aging treatment for 20 hours at of Ni-20Cr-20Fe-5Nb bulk alloy in which added as PCA, precipitates were formed, respectively. The precipitation temperatures of and in this bulk alloy were lower than those in commercial IN 718 alloy. It seemed that the lower precipitation temperatures for and in this bulk alloy than in commercial IN 718 alloy were due to severe plastic deformation during mechanical alloying.

1. The oxidation resistance of containing Ni-base alloy is superior to that of the alloy without . 2. The appearance of oxides of Ni-20Cr-20Fe-5Nb- alloy is similar to that of oxides in commercial PM1000 and MA754 alloy. 3. The oxides in ODS alloy are grown mainly at particle boundaries.