The role of the alloy matrix in the creep behavior of particle-strengthened alloys

Abstract

The more obvious strengthening microstructural features in heat-resistant super-alloys are oxide dispersoids and/or γ′ precipitates. An interesting problem is the role that the strength of the alloy matrix plays in the creep resistance of these alloys. We sought an answer to this problem through the evaluation of experimental data on a host of oxide-dispersion- and/or precipitation-strengthened nickel-based alloys with various levels of matrix solid solution strengthening and through a generalized expression for creep rates which separates the matrix contributions from the particle contributions to the resisting stress and creep strength of these alloys. It is concluded that the major role of the alloy matrix in the creep behavior of these alloys is in determining the apparent stress dependence of the creep rates. Specifically, the stronger the matrix through solid solution strengthening, the less applied stress sensitive is the creep rate of the alloy. The implications of these findings with respect to alloy design for better creep resistance in multiphase alloys are also discussed.