Abstract
Phosphorus is a primary contributor to interface fracture and embrittlement in steels because of its strong segregation tendency at grain boundaries (GBs). The lack of consistency in literature data imposes great difficulties in performing segregation modeling that is compatible with both the Langmuir-Mclean segregation theory and the thermodynamic description of the Bcc(Fe,P) phase. This work carefully evaluated experimental data for phosphorus segregation at GBs in α-Fe and provided a new formula for converting the auger electron spectroscopy (AES) peak height ratio to GBs. Based on newly assessed literature data, this work proposes that the major driving force for phosphorus segregation is the formation of Fe3P-type clusters at GBs, which is supported not only by the almost equivalent Gibbs energy of α_Fe using the Bcc(Fe,P) substitutional model and the Bcc(Fe,Fe3P, P) associate model, but also by the good agreement between thermodynamic/kinetic modeling results and experimental data.
Original language | English |
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Pages (from-to) | 134-141 |
Number of pages | 8 |
Journal | Calphad: Computer Coupling of Phase Diagrams and Thermochemistry |
Volume | 57 |
DOIs | |
State | Published - Jun 1 2017 |
Funding
This work was supported by the U.S. Department of Energy (DOE), Office of Nuclear Energy, Light Water Reactor Sustainability Research and Development Effort, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. Discussions with Drs. Pavel Lejček at the Institute of Physics, Academy of Sciences (Czech Republic), J. T. Busby, and K. Leonard at Oak Ridge National Laboratory (USA) are appreciated.