No abstract

The precipitation and strengthening behavior has been studied in a newly developed high molybdenum Ni-base superalloy, HASTELLOY ® C-22HS ® alloy, for long time exposures of 1000hrs at 600, 625 and 650ºC. The homogeneous precipitation of the long range ordered (LRO) phase Ni 2 (Mo,Cr) with an average size on the order of 10nm after a specially designed heat treatment contributes an excellent strengthening effect for this new superalloy. The grain boundary precipitation of high molybdenum containing phases such as M 6 C and μ phase has been studied via isothermal exposures in a wide temperature range of 600-1050ºC. The T-T-T curve of grain boundary phase precipitation has been also determined. This newly developed Ni-base superalloy with excellent corrosion resistance and high strength can be used in the intermediate temperature range below 650ºC.