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The performance of a newly developed multiprincipal-element alloy (MPEA) filler metal for brazing of nickel-based superalloys was directly compared to a conventional boron- and silicon-suppressed filler (BSSF) metal. The comparison was demonstrated on an Alloy 600 substrate with a brazing temperature of 1200°C. Single-phase solidification behavior and the absence of boron and silicon in the MPEA led to a joint microstructure devoid of eutectic constituents or brittle phases in brazes employing this filler metal. In the brazes using the conventional BSSF metal, incomplete isothermal solidification and subsequent athermal solidification of the residual liquid resulted in large particles of a chromium-rich boride phase distributed throughout the microstructure. Tensile testing of brazed butt joints at both room temperature and 600°C testing conditions demonstrated that the MPEA joints exhibited total ductility values at least one order of magnitude greater than that of BSSF joints, but they showed comparable yield strengths in both testing conditions. Fractographic assessment confirmed that boride phases nucleated cracks and resulted in brittle failure in the BSSF joints, while the MPEA joints exhibited extensive ductile microvoid coalescence. Fine-scale porosity and oxide inclusions may be the dominant factors limiting the overall ductility observed in the MPEA brazes.
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This content will become publicly available on February 1, 2026
Liquid Metal Embrittlement Elimination in RSW of Galvannealed AHSS DP980
Liquid metal embrittlement (LME) is a longstanding problem for resistance spot welding (RSW) of Zn-coated automotive sheet steels, especially third generation advanced high-strength steels (AHSSs). This work designed a multi-principal element alloy (MPEA), considered a high entropy alloy (HEA), that preferentially absorbs Zn during RSW and forms a single solid solution phase. The MPEA composition was designed using a highthroughput multi-physics-based analysis, which down-selected the FeMnNiCoZn system as favorable to present a single face-centered cubic (FCC) phase over a broad dilution composition space with the substrate. Comparing the welds made with MPEA foils to control welds without the MPEA, optical microscopy revealed no visible LME cracks in MPEA welds, whereas Zn-lined cracks with a length of 5–100 μm populated the control welds. Energydispersive spectroscopy demonstrated the MPEAlimited Zn penetration distance into the AHSS grain boundaries to less than 10 μm. Kinetic simulations also predicted the MPEA would retain Zn as a solid solution and limit its penetration into the AHSS substrate. Site-specific synchrotron diffraction confirmed a single FCC phase in the MPEA and an unaffected ferrite/martensite microstructure in the adjacent DP980 AHSS substrate. Furthermore, tensile-shear tests showed average improvements of 21% in peak load and 80% in fracture energy in welds employing MPEA foils when welded with the same current and schedule.
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- Award ID(s):
- 1847630
- PAR ID:
- 10624912
- Publisher / Repository:
- Welding Journal
- Date Published:
- Journal Name:
- Welding Journal
- Volume:
- 104
- Issue:
- 04
- ISSN:
- 0043-2296
- Page Range / eLocation ID:
- 119 to 130
- Subject(s) / Keyword(s):
- Liquid Metal Embrittlement Resistance Spot Welding Galvannealed Advanced High Strength Steel Multi-Principal Element Alloy High Entropy Alloy
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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