TY - JOUR A1 - Ikeda, Yuki A1 - Ni, H.C. A1 - Chakraborty, A. A1 - Ghassemi-Armaki, H. A1 - Zuo, J.M. A1 - Darvishi Kamachali, Reza A1 - Maaß, Robert T1 - Segregation-induced grain-boundary precipitation during early stages of liquid-metal embrittlement of an advanced high-strength steel T2 - Acta Materialia N2 - Liquid-metal embrittlement (LME) of galvanized (Zn-coated) advanced high-strength steels is a long-known problem in materials science. Here we reveal the initial microstructural processes underneath the Zn-coating that lead to LME-microcrack initiation in the steel substrate. We track the microstructural evolution during the first tens of milliseconds and find pronounced signatures of Fe-Zn intermetallic precipitation in both ferrite grain boundaries and at internal ferrite-oxide phase boundaries. In concert with novel CALPHAD-integrated density-based thermodynamic modelling, we demonstrate that Zn-rich intermetallic phase-nucleation can occur at markedly low processing temperatures due to a segregation transition. We show that a small Znenrichment caused by Zn bulk-diffusion during the initial temperature rise in a joining process is sufficient to induce the segregation transition and subsequent nucleation of Fe-Zn intermetallic grain-boundary phases, which the experiments link to crack initiation sites. These findings direct focus onto LME-controlling microstructural and thermodynamic phenomena at temperatures below the ductility trough and the austenite formation temperature. PB - Elsevier Ltd KW - Resistance spot welding KW - Liquid-metal embrittlement KW - Steels KW - Grain boundaries PY - 2023 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/58106 AN - OPUS4-58106 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581067 VL - 259 SP - 1 EP - 12 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany