Interfacial structure and formation mechanism of 90 W-7Ni-3Fe/steel using co-sintering method

Abstract

In this study, we proposed a powder metallurgy method to develop an interlocking interface in tungsten heavy alloy/steel composites, which is achieved by co-sintering technology using tungsten heavy alloy and steel powders with a large difference in particle size. The interfacial microstructure evolution and mechanical properties of the co-sintered joint as a function of co-sintering temperature were investigated systematically. Results showed that a well-bonded interlocking interface was formed along the steel particles as a result of the tungsten heavy alloy particles filling in the gaps between two neighboring steel particles. The co-sintered joint contains four regions: the W alloy matrix, the Fe3W3C layer, the Ni-affected layer, and the steel matrix. Based on the microstructural characterization, the interface formation mechanism and reaction layer growth behavior are discussed in depth. Benefitting from the interlocking structure, the highest tensile strength of the co-sintered specimen is 265 MPa, which is 66% higher than that of the non-interlayer joint obtained by diffusion bonding method. Moreover, its performance is better than that of some W alloy/steel with an interlayer. This technique offers a potential method for the efficient preparation of a W alloy/steel composite structure with outstanding properties.