Microstructural Evolution of Cr-Cu Composites in Liquid-Phase Sintering

Abstract

The paper examines the effect of temperature and volume fraction of refractory particles on their growth kinetics during liquid-phase sintering of Cr–Cu composites in the temperature range 1150–1350 ⁰C under a vacuum of (2–4) · 10^–3 Pa. It is established that the growth kinetics of mean-size particles is described by a near-cubic law and the decrease in their number is determined by a near-inverse dependence: the apparent activation energy (Q = 113 ± 10 kJ/mol) is of the order of magnitude close to that of diffusion in liquid metals. Diffusion-controlled particle growth is established according to the Lifshitz–Slezov–Wagner theory (LSW theory) and based on the signs of diffusion coalescence. Experimental growth constants are one order of magnitude higher than those calculated within the classical LSW theory. The increase in growth rate constant with volume fraction of refractory particles varying from 0.4 to 0.7 and the change in particle size distribution function after 90 min sintering at 1200 ⁰С are consistent with Ardell' model, which modifies LSW theory considering the effect of volume fraction of particles on their growth kinetics.