Effect of Ag addition on the as-cast microstructure of Cu–8 wt.% Fe in situ composites

Ternary copper-based composites consisting of Cu, 8 wt.% Fe and 0.1–6 wt.% Ag were prepared by inductive melting and casting. The effect of Ag addition on the as-cast microstructure was investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The results show that the primary Fe dendrites in the as-cast microstructure are refined significantly with the presence of Ag. Contact angle between Cu–Ag alloy and γ-Fe was measured using sessile drop technique to investigate the refinement mechanism of the primary Fe dendrites. In addition, the effect of Ag addition on the dissolution of Fe atoms in the Cu matrix at high temperature was investigated by means of energy dispersive X-ray spectroscopy (EDS). The results show that the presence of Ag inhibits the solubility of Fe in the Cu matrix at high temperature.

Research highlights▶ Ag addition refines the primary Fe dendrites. ▶ Ag inhibits the solubility of Fe in Cu matrix at high temperature. ▶ Refinement mechanism is explained by wetting properties between Cu–Ag and γ-Fe.