Diffusion bonding of iron aluminide Fe72Al28 using a copper interlayer

An Fe72Al28 alloy was diffusion-bonded using a copper interlayer under vacuum at 1075 °C for 1 h, 2 h, 4 h and 6 h durations at 3.2 MPa applied pressure. The bond microstructure was found to be composed of the copper rich interlayer, copper rich precipitates and the base metal. SEM-EDS studies indicated major diffusion of aluminium and iron atoms from Fe72Al28 into the copper interlayer and copper atoms from the copper interlayer into the Fe72Al28 matrix. SEM observations of fractured surfaces of the diffusion-bonded samples showed some plastic deformation and signs of good bonding. Cu3Al and B2–FeAl-based phases were identified by SEM-EDS and X-ray diffraction studies at the bond and on the fracture surfaces of all samples investigated. Good bonding was achieved with a maximum shear strength of 298 MPa which is 65% of the parent material shear strength for a sample diffusion-bonded for 6 h.