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Observation of grain boundary segregation on an atomic scale in a Fe-0. 04% P alloy by atom-probe FIM
Grain boundaries introduced intentionally in a Fe-0.04% P alloy by cold-working were successfully observed using a field ion microscope (FIM), and the composition along a grain boundary was analyzed using a high-performance time-of-flight atom-probe. Phosphorus was found to segregate to the grain boundaries below 600/sup 0/C, in agreement with previous Auger electron spectroscopy studies. In addition to P, it was found that several other elements, such as Ti, O, C and Mn segregate to the grain boundaries at different annealing temperatures
An Evaluation of the Fe-N Phase Diagram Considering Long-Range Order of N Atoms in γ'-Fe4N1-x and ε-Fe2N1-z
The chemical potential of nitrogen was described as a function of nitrogen content for the Fe-N phases α-Fe[N], γ'-Fe4N1-x, and ε-Fe2N1-z. For α-Fe[N], an ideal, random distribution of the nitrogen atoms over the octahedral interstices of the bcc iron lattice was assumed; for γ'-Fe4N1-x and ε-Fe2N1-z, the occurrence of a long-range ordered distribution of the nitrogen atoms over the octahedral interstices of the close packed iron sublattices (fcc and hcp, respectively) was taken into account. The theoretical expressions were fitted to nitrogen-absorption isotherm data for the three Fe-N phases. The α/α + γ', α + γ'/γ', γ'/γ' + ε, and γ' + ε/ε phase boundaries in the Fe-N phase diagram were calculated from combining the quantitative descriptions for the absorption isotherms with the known composition of NH3/H2 gas mixtures in equilibrium with coexisting α and γ' phases and in equilibrium with coexisting γ' and ε phases. Comparison of the present phase boundaries with experimental data and previously calculated phase boundaries showed a major improvement as compared to the previously calculated Fe-N phase diagrams, where long-range order for the nitrogen atoms in the γ' and ε phases was not accounted for
Propriedades mecânicas e de corrosĂŁo de dois aços inoxidáveis austenĂticos utilizados na fabricação de implantes ortopĂ©dicos
Corrosion by carbonaceous gases, carburization and metal dusting, and methods of prevention â€
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