Microstructural characteristics in vacuum TLP (Transient Liquid Phase) bonds using a novel iron-based interlayer based on duplex stainless steel base metal alloyed with a melting-point depressant

• A novel method of manufacturing filler based on base metal and boron was developed.
• Cr boride and B nitride appeared in the residual liquid for 60 s at 1250 °C.
• After isothermal solidification, element distribution was comparably uniform.
• After isothermal solidification, bond and substrate exhibited a similar composition.
• After isothermal solidification, joint was free from Cr boride and B nitride.

A novel method of manufacturing iron-based interlayer based on a duplex stainless steel and a melting-point-depressant element (B) was developed. As the B content was enhanced in the range of 0–3.93 wt.%, the melting temperature of the produced alloy decreased. Transient liquid-phase (TLP) bonding of the duplex stainless steel was carried out using a selected filler material with 3.93 wt.% B and the microstructural features across the joint region were investigated. Before completion of isothermal solidification, Cr boride and B nitride secondary-phases appeared in the residual liquid. Isothermal solidification of the residual liquid was completed after 7200 s at 1250 °C and then the distribution of every element across the joint was comparably homogeneous. Furthermore, the bonding region and the base metal exhibited a similar composition, and the joint was free from Cr boride and B nitride particles.