Effects of the deformed volume and the volume fraction on the local deformation behavior of W/Cu composites

Copper reinforced by tungsten particles has high potential applications in the fields of electronics and electric contacts where high strength accompanied with good electrical conductivity is required. The effects of different scaling parameters (deformed volume, tungsten volume fraction and the tungsten particle size) affect the force needed for the machining of the W/Cu particle reinforced composites. W/Cu composites with different weight percentages of tungsten (80, 70 and 60 wt.%) were tested under compression loading. Different sizes of the compression specimens were tested; the specimen diameter Ds was varied to be 1, 2, 4, 6 and 8 mm. The effect of the tungsten particle size was varied to be 10 and 30 mu m. The compression tests were done at strain rates of 0.1s(-1). The experiments were carried out within a temperature range from 20 degrees C to 800 degrees C. The mechanically tested specimens were metal lographically investigated to determine the degree of deformation of the tungsten particles in different specimen geometries. A clear dependence of the flow stress on the volume of the deformed specimens and the tungsten volume fraction was found. This size effects were more obvious with increase of the tungsten volume fraction at lower temperatures. The metallographic investigation was helped to understand the observed size effect of the composites in relation to the volume fraction and the specimen size.