Evaluations of nanomechanical and indentation creep of diffusion-bonded aluminum and austenitic stainless steel joint interface

Diffusion bonding of aluminum alloy (AA-7075) with austenitic stainless steel (AISI 304L) was performed in the environment of Argon inert gas. The resultant bonding interface was investigated for its mechanical, nanomechanical, microstructural, and compositional characteristics using lap shear tests, nanoindentation and indentation creep, as well as optical (OM) and scanning electron microscopy (SEM), with energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results revealed that intermetallic compounds (IMCs) of FeAl₃, FeAl₂, FeNi₃, and Fe₃Ni₂ were formed at the bonding interface. Similarly, a nano hardness of 3.5 GPa occurred at the bonding interface which was 15% and 454% higher as compared to base metal (BM) of AISI 304 and AA-7075 respectively. Additionally, indentation creep showed that the bonding interface has higher creep resistance compared to other bonding zones (BZ). Lastly, an average shear strength of 67 MPa was achieved with a joint efficiency of 58%.