Microstructures and properties of silver-based contact material fabricated by hot extrusion of internal oxidized Ag–Sn–Sb alloy powders

In the present study, powder internal oxidation and hot extrusion were used to prepare silver metal oxide (Ag-MeO) contact materials. Water atomized Ag–5.08 wt.%Sn–3.15 wt.%Sb alloy powders were internal oxidized and hot extruded with extrusion ratios of 49:4 and 49:1. The microstructures of composite powders and final products were studied by OM, SEM and TEM in details. The distribution of oxide particles in silver matrix are highly depended upon extrusion ratios. The oxide particles refined by the fracture of oxide clusters and distributed more uniform in the 49:1 extrusion. SnO2 and Ag1.7Sb2O5.77 are two kinds of reinforced particles identified. The influence of extrusion ratio and following anneal treatment on the properties, including of density, Vickers hardness and electric conductivity, were discussed. The best performance exhibited on the annealed sample of 49:1 extrusion, with density, Vickers hardness and electrical conductivity of 9.83 g/cm3, 91.6 HV and 71%IACS, respectively.