Coarsening behaviour of a Ni-base superalloy under different heat treatment conditions

Nickel-base superalloys are used in applications requiring strength at high temperatures. Most of these alloys are precipitation hardened by a gamma'[Ni-3(Al, Ti)] phase coherently precipitated in a fcc matrix. The properties and resistance to microstructural changes at high temperatures depend on factors as particle size, coarsening rate, distribution and volume fraction of the gamma' precipitate, factors that can be modified through different heat treatments. The present work describes the effect of heat treatments to produce different gamma' precipitate sizes and distribution in a CMSX-2 superalloy. Using subsequent aging treatment at constant temperature, we studied the evolution and growth of such precipitate particles and determined the activation energy for coarsening. (C) 2007 Elsevier B.V. All rights reserved.