Experimental investigation and modeling of the influence of microstructureon the resistive conductivity of a Cu-Ag-Nb in situ composite

A Cu-8.2 wt% Ag-4 wt% Nb in situ metal matrix composite was manufactured by inductive melting, casting, swaging, and wire drawing. The final wire (eta =ln(A(o)/A) = 10.5, A: wire cross section) had a strength of 1840 MPa and 4 6% of the conductivity of pure Cu. The electrical resistivity of the compos ite wires was experimentally investigated as a function of wire strain and temperature. The microstructure was examined by means of optical and electr on microscopy. The observed decrease in conductivity with increasing wire s train is interpreted in terms of inelastic electron scattering at internal phase boundaries. The experimental data are in very good accord with the pr edictions of an analytical size-effect model which takes into account the d evelopment of the filament spacing as a function of wire strain and the mea n free path of the conduction electrons as a function of temperature. The e xperimentally obtained and calculated resistivity data are compared to thos e of the pure constituents. (C) 1999 Acta Metallurgica Inc. Published by El sevier Science Ltd. All rights, reserved.