The effect of long-term thermal exposures on the microstructure and properties of CMSX-10 single crystal Ni-base superalloys

The long-term thermal stability of CMSX-10 single crystal superalloys has been studied as a function of heat treatment and thermal exposure. The CMSX-10 alloys were subjected to long-term unstressed heat treatments at temperatures of 950 and 1050degreesC for periods of 1000 and 10.000 h. The microstructures and creep properties of the samples before and after long-term thermal exposures were characterized. The gamma' coarsening was observed after all exposures and the formation of topologically close packed (TCP) phases was observed in both samples exposed at 1050 degreesC and the 10 kh exposure at 950 degreesC. High temperature creep tests were carried on these samples at 950 degreesC at an engineering stress of 310 MPa. The creep lives were found to deteriorate with the increase in exposure time and temperature as a result of the microstructural degradation. The coarsening of the gamma' precipitates was observed to be the main factor in the degradation of the properties. (C) 2004 Elsevier B.V. All rights reserved.