The effect of sintering temperature on the tensile properties and fracture behaviors of W/Ta multilayer composites

Abstract

In this study, a series of the W/Ta multilayer composites are prepared by spark plasma sintering (SPS) at different temperature. The relationship between the sintering temperature and tensile properties are investigated in detail. Large equiaxed recrystallization grains appear in the W layers when the sintering temperature reaches 1200 °C. The W/Ta multilayer composites have a better comprehensive performance when the sintering temperature is 1100 °C. The fracture mechanisms of the W/Ta multilayer composites can be divided into two types based on the bonding strength of the interface. When the sintering temperature is lower than 1200 °C, delamination cracks can be seen. Meanwhile, necks and shear cracks appear in the Ta layers. When the sintering temperature reaches 1200 °C, delamination cracks disappear. Meanwhile, a lot of shear bands can be observed in the Ta layers. As the sintering temperature increases, the fracture mode of the W layers changes from transgranular cleavage fracture to intergranular fracture. And the fracture mode of the Ta layers is always ductility fracture. However, the ductility of the Ta layers decreases since the stress state changes from plane stress state to plane strain state. The tensile strength of the W/Ta multilayer composites can be calculated by the proposed model considering the stress concentration factor in the interface.