Abstract: Prolonged tension tcsts were caTried out by comblning elevated temperatures with declined stresses over thc range of 760-1050° C and 780-115MPa. The effects of temperature and applied stress on rupture life, and the relations of temperuture, applied stress and mpture life to characteristic dimensions of coherent phases (γ matrix channel width and mpcd γ precipitate thickness), and to the elongation as well as to the cross sectional area reduction of thc tested specimens were investigated. Under all testing conditions, longittLdinal coalescence of seveml adjacent armys of γ precipitates could occur to dtherent extents along the direction of the applied stress axis in addition to their normal directional coarsening. The extent of γ Longitudinal coalescence became increased and its morphology tended to be irmpular with the increase of temperuture although the applied stresses were relatively lower.

Key words: superalloy CMSX-2, prolonged tension, characteristic-dimension, longitudinal coalescence