Microstructure and mechanical properties of single-crystal diamond/Kovar alloy joints brazed with an AgCuTi metal filler

Abstract

Joining single-crystal diamond with the Kovar alloy has great application potential in the field of optoelectronic devices. In this work, single-crystal diamond was brazed with a Kovar alloy by using an AgCuTi metal filler at a temperature of 830 °C with a dwell time of 5 min. The corresponding microstructures and interfacial products of the brazed joints were systematically studied. AgCuTi interacts with diamond, and a continuous TiC reaction layer with a thickness of 0.5–1 μm forms at the interface between diamond and the residual AgCuTi metal filler. In contrast, there is no obvious reaction layer at the interface between the Kovar alloy and the residual metal filler; however, it is observed that the metal filler penetrates the Kovar alloy along the grain boundary of the Kovar alloy. In addition, the compression shear strength of the brazed joint was tested, and the fracture morphologies were analysed. The maximum shear strength of the brazed joint is 102.73 MPa, and the fracture shows mixed ductile and brittle characteristics.