Infiltrated Cu8Al-Ti alumina composites

The effect of titanium additions on the interface and mechanical properties of infiltrated Cu8 wt%Al-Al2O3 composites containing 57 +/- 2 vol% ceramic are investigated, exploring two different Al2O3 particle types and four different Ti concentrations (0, 0.2, 1, 2 wt%Ti). Addition of 0.2 wt%Ti leads to the development of a thin (5-10 nm) layer enriched in Ti at the interface between Cu alloy and Al2O3 particles; this Ti concentration produces the best mechanical properties. With higher Ti-contents Ti-3(Cu,Al)(3)O appears; this decreases both the interface and composite strength. Composites reinforced with vapor-grown polygonal alumina particles show superior mechanical properties compared to those reinforced by angular comminuted alumina particles, as has been previously documented for aluminum-based matrices. Micromechanical analysis shows that damage accumulation is more extensive, as is matrix hardening by dislocation emission during composite cooldown, in the present Cu8 wt%Al matrix composites compared with similarly reinforced and processed Al-matrix composites. (C) 2014 Elsevier Ltd. All rights reserved.