Interface microstructure and mechanical properties of diffusion bonded joints between tungsten and ferritic steel with vanadium interlayer

The interface characteristics between W and ferrite steel (FS) diffusion welded with a V interlayer of 0.5mm in thickness was investigated in vacuum hot pressing furnace at 1050℃ for 1h and 10 MPa.Microstructures,element compositions and micro-hardness of joint were analyzed and tested with field-emission scanning electron microscopy (FE-SEM),energy dispersive spectroscopy (EDS) and nanoindenter,respectively.Tensile strength was tested with mechanical test machine.Results showed that,a reliable bonding on W/FS interfaces by means of diffusion welding between matrix and V interlayer was obtained.The W/FS joint is a multilayer sandwich structure, which includes the transition zone of W/V,the residual V interlayer and the diffusion layer of V/FS.Meanwhile,the transition zone of W/V was mainly composed of a solid solution structure and the V/FS diffusion layer with the highest hardness where there was a definite structure of V/VC layer/decarburized layer/FS.The tensile strength of joint reaches 75MPa and V/FS interface is main fracture source because of containing brittle VC phase.