SEPARATION OF MACROSCOPIC, ELASTIC MISMATCH AND THERMAL-EXPANSION MISFIT STRESSES IN METAL-MATRIX COMPOSITE QUENCHED PLATES FROM NEUTRON-DIFFRACTION MEASUREMENTS

Neutron diffraction measurements of the strain profile in a quenched p late of an aluminium-dash; silicon carbide particle-reinforced metal m atrix composite are reported. The results have been used to evaluate t he efficacy of an analysis technique which allows distinction of the s tiffness mismatch and shape misfit stresses between the matrix and rei nforcement, as well as between these and any macrostress present. The analysis is presented for measurements made on a metal matrix composit e plate which, as a consequence of quenching from elevated temperature , shows large variations in residual stress as a function of position through the plate thickness. The measurements illustrate the additiona l insight which can be obtained through the separation of the elastic mismatch and thermal misfit stresses. The stress components thus obtai ned show good agreement with calculated long-range residual and mismat ch stresses. (C) 1997 Acta Metallurgica Inc.