Functionally graded aluminum matrix composites produced by centrifugal casting

A model for steady state deformation of the commercial γ′ precipitation hardened alloy A286 at moderately high temperature is presented. This model is mainly based on the theory of thermally activated glide. The activation parameters such as the maximum free energy necessary to overcome obstacles to glide, the threshold stress for jerky glide and the activation volume of the rate controlling process are derived from experimental results and allowed rationalization of all the measurements in the range of stresses and temperatures investigated. Creep tests were carried out at constant stress in the range of 180–750 MPa at 600, 640, 670 and 700 °C in air. Transmission electron microscopy has permitted determination of the size of the γ′ particles and the average distance between them.