High-temperature oxidation behavior of the Co-base superalloy DZ40M in air

The oxidation behavior of the Go-base superalloy DZ40M was studied in air at 900-1100 degrees C for times of up to 2000 hr. The results indicated that this alloy can grow a protective oxide scale at 900 and 1000 degrees C during isothermal oxidation, but not at 1100 degrees C because of serious cracking cmd spalling of the oxide scales. Moreover, an internal-precipitate zone formed in the subsurface region of the alloy at all temperatures and times. The precipitates, were rich in Cr in the vicinity of the ahoy-scale interface and rich in Al deep in the alloy. The internal-precipitate morphology changed from a granular to needlelike shape with increasing oxidation temperature.