Thermal residual strains and stresses in Al2O3/Al composites with interpenetrating networks

Thermal expansion data for Al2O3/Al interpenetrating network composites, obtained using a dilatometer, are analysed to determine the residual stress during, and after, thermal cycling between room temperature and 600 degrees C. A rigorous technique, using the effective medium approximation method, is applied, utilizing unconstrained thermal strains of the individual phases which are determined experimentally. Coefficients of thermal expansion are predicted as a function of metal content and temperature. Residual stresses are calculated using two approaches: (1) a "macroscopic" approach which considers total composite strain and (2) a "micromechanical" approach which considers time dependent effects in the metal phase. Predictions agree well with experimental data and neutron diffraction measurements, and provide a mechanistic understanding of the thermo-mechanical behaviour of the material. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved