Author(s)

D.J. Arrell & J.L. Valles

Abstract

A model for microstructural evolution in super alloys subjected to an applied stress D.J. Arrell, J.L. Valles Institute for Advanced Materials, Joint Research Centre, 1755 ZG Petten, The Netherlands ABSTRACT We present a recently developed criterion to predict the 'rafting', or anisotropic coarsening of the y-y' microstructure, in nickel - base single crystal superalloys subjected to externally applied stresses at elevated temperatures. Our simple criterion is based on the anisotropy of the energy associated with the y-y' interfacial mismatch dislocations, which is caused by the application of stress to the system, and it includes the external load and temperature dependence. Monte Carlo simulations incorporating the anisotropic growth by means of the new criterion compare successfully with rafting behaviour observed during creep tests. INTRODUCTION Lifetime prediction capabilities for critical components such as turbine blades in aero-engines can be enhanced by

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