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

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 degrees 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 degrees 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. (c) 2013 Elsevier B.V. All rights reserved.