The effect of additive and sintering mechanism on the microstructural characteristics of W–40Cu composites

Abstract

In this research, effect of cobalt and nickel additives on the W–40wt.% Cu composites prepared by solid phase sintering and infiltration (SPS+I) as well as liquid phase sintering (LPS) processes has been investigated. For this purpose, three types of powder consist of pure tungsten, mixture of tungsten–1wt.%Co and mixture of tungsten-1wt.%Ni were separately prepared and compacted by cold isostatic pressing (CIP). In the SPS+I process, compacted specimens were sintered at 1100°C for 1h and subsequently infiltrated by liquid copper at 1250°C for 1h. In the LPS process, compacted samples were directly infiltrated without initial sintering. Density of samples was measured by Archimedes method. Microstructure (i.e. contiguity, porosity, grain size) and chemical composition were studied by SEM and EDS, respectively. It is found that microstructural characteristics of the W–40wt.%Cu composites depend on sintering mechanism as well as additive type. Density of samples prepared by LPS process was higher in compared with ones obtained via SPS+I process. This behavior was related to W–W contiguity as well as tungsten particles wettability.