Characterisation of interface in diffusion bonded Fe 3 Al/Q235 carbon steel dissimilar material

Abstract

Phase structure characteristics near the interface of Fe₃Al/Q235 carbon steel diffusion bonding are researched by means of X-ray diffraction and TEM. The test results indicated that an obvious diffusion transition zone was formed near the Fe₃Al/Q235 carbon steel interface under the conditions: heating temperature 1050 - 1100°C, holding time 60 min and pressure 9.8 MPa. The diffusion transition zone consisted of Fe₃Al and α-Fe (Al) solid solution. The microhardness near the diffusion transition zone was 480 - 540 HV(25 g). There was no brittleness phase of high hardness in the diffusion transition zone. This is favourable for increasing the toughness of a Fe₃Al/Q235 diffusion joint. There was a crystal orientation relationship of (110) _α-Fe(Al)//(011)_Fe3Al and [001]_α-Fe(Al)//[100]_Fe3Al between the Fe₃Al phase and the α-Fe (Al) solid solution in the diffusion transition zone.