Microstructure and Fracture of 50Mo-50Re Vacuum Brazed with Fe-Si-B Filler Metal

Abstract

Microstructural evolution, interfacial reaction and fracture during vacuum brazing of 50Mo-50Re alloys using amorphous alloy Fe-5.6Si-2.6B(wt%) were investigated. A binary intermetallic compound, σ(Mo 2 Re 3) formed as parallel contiguous layers in the diffusion zone. In addition, Fe from the braze alloy, in combination with dissolved Mo from the substrate, formed two layers of binary compounds μ-Mo 6 Fe 7 and λ-MoFe 2 , adjacent to diffusion zone. The unreacted Fe-based filler metal solidified as α-Fe solid solution. Fracture analysis showed that the mode of failure was mainly transgranular cleavage with partly intergranular and the fracture located on the interface of 50Mo-50Re alloy and the central area of brazing seam.

A Preliminary Study of New Experimental Low-Cost Fe–P-Based and Mn–Fe–P-Based Brazing Filler Metals for Brazing of Non-Alloy and Low-Alloy Steels

“…Fe-Ni-B was mentioned for the first time in 1998, together with Fe-Ni-Si-B, which had already been previously mentioned in the scientific literature [9]. In the 21st century, there was not a lot of development on new alloy systems, with most merely modifying the compositions of existing filler metals, such as Fe-B-Si-and Fe-Cr-B-Si-based alloys [10][11][12]; Fe-Cr-based alloys with additions of Co and/or Ni, W, Mo as well as B and Si [13]; Fe-Cr-based alloys with addition of Si and P [14]; Fe-Cr-based alloys with addition of P and B [15]; Fe-Ni-based filler metals with addition of Mo and B [16]; and Fe-Ni-Cr-based filler metals in various combinations with other alloying elements and a combination of melting point depressants B, Si, P, and C [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. New developments in this period are Fe-Al-Si and Fe-Al-Si-Mo filler metals for brazing iron aluminides [31] and Fe-Ni-based filler metal with between 10.0 wt% and 20.0 wt% of a combination of melting point depressants C, P, Si, and B [32].…”