Investigation of Tungsten/Steel Jointing Based on W-Fe-Cr Mixed Powder Interlayer AITranslate

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Chinese Library Classification Number:TG457.1[金属学及工艺—焊接]

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Tungsten(W)and oCr13Al steel were jointed in vacuum under the conditions of 5 MPa pressure and heat preservation at 1120 ℃ for 60 min with 90W-8.5Fe-1.5Cr(w/%)mixed powder as the interlayer and pure copper foil as the brazing filler metal.The particle size distribution and morphology of the WFe-Cr mixed powder were studied by laser particle size analyzer and SEM,and the microstructure,composition,mechanical properties and fracture characteristics of the joints were studied by SEM,EDS and electronic universal tester.The results show that the joint is composed of tungsten base metal/W-Fe-Cr heavy alloy layer/steel base metal,in which the W-Fe-Cr heavy alloy layer is formed through solid-phase sintering of W-Fe-Cr mixed powder.Also,the W-Fe-Cr heavy alloy layer/tungsten base metal interface is brazed through an extremely thin brazing seam,while the W-Fe-Cr heavy alloy layer/steel base metal interface is joined by brazing at first and then solid-phase diffusion welding.High-energy ball miling of W-Fe-Cr mixed powder plays a key role in densification and homogenization of W-Fe-Cr heavy alloy layer under relatively low jointing pressure.The shear strength of the tungsten/steel joints is 41 MPa and all joints were fractured near the interface of tungsten base metal and W-Fe-Cr heavy alloy layer with brittle fracture characteristics.This study provides a new idea for the design of tungsten/steel joint interlayer with adjustable linear expansion coefficient and without active element Ni,which is useful for further improving the applicability of tungsten/steel joint structure in nuclear fusion reactors.