Investigation of Mechanical and Microstructural Characteristics of Diffusion-Bonded CpAl/IN718 Interface

Abstract

Diffusion bonded joint of Commercially Pure Aluminum (CpAl) with Inconel 718 (IN718) superalloy was investigated for its mechanical and microstructural characteristics. Diffusion Bonding (DB) of CpAl/IN718 was performed at 500 °C for 60 minutes using vacuum tube furnace in the presence Argon (Ar) gas under pressure at a heating rate of 10 °C/minutes followed by furnace cooled. The resultant joint interface was investigated by using Optical and Scanning Electron Microscopy (OM and SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), microhardness and shear strength. The microstructural analysis shows the formation of various Intermetallic Compounds (IMCs) at the bonding interface, such as NiAl3, FeAl2, FeAl3, Fe2Al5 along with austenitic matrix, which was confirmed by XRD. Additionally, the hardness of the bonding interface was 15% and 255 higher as compared to BM of IN718 and CpAl respectively. Lastly, an average lap shear strength of 61 MPa was achieved with a joint efficiency of 84%.