Preferential Au precipitation at deformation-induced defects in Fe–Au and Fe–Au–B–N alloys

• Published in: Journal of alloys and compounds 2014-01, Vol.584, p.425-429
• Main Authors: Zhang, S., Langelaan, G., Brouwer, J.C., Sloof, W.G., Brück, E., van der Zwaag, S., van Dijk, N.H.
• Format: Article
• Language: English
• Subjects: Alloys; Au precipitation; Condensed matter: structure, mechanical and thermal properties; Creep; Creep tests; Cross-disciplinary physics: materials science; rheology; Crystal defects; Deformation; Exact sciences and technology; Ferrous alloys; Gold; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals and alloys; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Plastic deformation; Precipitation; Segregations; Self-healing; Surface segregation
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.09.011

•Fe–Au–B–N forms a good model alloy system for self healing of deformation damage.•Solute Au atoms exclusively precipitate at grain boundaries, cracks and cavities.•XPS indicates a strong tendency for Au segregation on free surfaces at 550°C.•Interstitial B and N form hexagonal BN on free surfaces at 550°C.•Selective Au precipitation at open volume defects can cause autonomous repair. The influence of deformation-induced defects on the isothermal precipitation of Au was studied in high-purity Fe–Au and Fe–Au–B–N alloys. Preferential Au precipitation upon annealing at 550°C is observed at local plastic indentations. In fractured Fe–Au–B–N, solute Au atoms were found to heterogeneously precipitate at grain boundaries and local micro-cracks. This is supported by in-situ creep tests that showed a strong tendency for Au precipitation at cracks and cavities also formed during creep loading at 550°C. Complementary X-ray photoelectron spectroscopy experiments indicate a strong tendency of Au, B and N segregation onto free surface during aging. The observed site-specific precipitation of Au holds interesting opportunities for defect healing in steels subjected to creep deformation.