Effect of phase transformation and intermetallic compounds on the microstructure and tensile strength properties of diffusion-bonded joints between Ti–6Al–4V and AISI 304L

The occurrence of a phase transformation and the effect of intermetallic compounds on the microstructure and tensile strength properties of diffusion-bonded (DB) joints between Ti–6Al–4V and AISI 304L were studied in the temperature range of 875–950 °C with an interval of 25 °C, a bonding time of 60 min and pressures of 4 MPa and 8 MPa. A maximum tensile strength of 242.6 MPa, was observed for diffusion-bonded joints that were processed at a temperature of 900 °C, bonded for 60 min at a pressure of 4 MPa and annealed for 2 h at 750 °C. Optical microscopy and scanning electron microscopy (SEM) were used to examine the grain growth and the fine details of the interface structure. Energy dispersive X-ray analysis (EDAX) and X-ray diffraction analysis (XRD) revealed the existence of intermetallic compounds and corroborated the phase transformation.

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► Samples processed at 900 °C exhibited a maximum tensile strength of 242.6 MPa.
► Annealed samples exhibited more strength than the samples with no heat treatment.
► At higher temperatures, the reaction zone width increased for the annealed samples.
► A maximum hardness value of 781 VHN was noted for the samples processed at 950 °C.
► XRD report revealed Fe2Ti, Mn2Ti, Ti2Si2, Fe2V3, All4CrNi15, and Fe3Al2Si4.