Langelier Brian, Van Landeghem Hugo P, Botton Gianluigi A, Zurob Hatem S
1Department of Materials Science and Engineering,McMaster University,1280 Main St. W.,Hamilton,ON,Canada.
2SIMaP,UMR 5622,Grenoble INP - CNRS - UGA,1130 rue de la piscine,BP75,F-38420 St Martin d'Hères,France.
Microsc Microanal. 2017 Apr;23(2):385-395. doi: 10.1017/S1431927617000150. Epub 2017 Mar 21.
Improved understanding of the interactions between solutes and the austenite/ferrite interface can benefit modeling of ferrite growth during austenite decomposition, as the transformation kinetic is significantly affected by solutes that influence interface mobility. Solute-interface interactions dominate solute segregation at the interface in binary systems, but in multi-component alloys, solute-solute interactions may also affect segregation. In this study, interface segregation in Fe-Mn-N is examined and compared with Fe-Mn-C, to reveal the extent to which C affects the segregation of Mn. Atom probe tomography (APT) is well-suited to analyze solute concentrations across the interface, as this technique combines high spatial resolution and compositional sensitivity. Measurements of Mn show that segregation is only observed for Fe-Mn-C. This demonstrates that Mn segregation is primarily driven by an affinity for C, which also segregates to the interface. However, the measurement of N in steels by APT may be affected by a variety of experimental factors. Therefore, in verifying the Fe-Mn-N result, systematic examination is conducted on the influence of pulsing method (voltage versus laser), sample preparation (ion milling versus electropolishing), and vacuum storage on the measured N concentration. Both laser pulsing and focused ion beam sample preparation are observed to decrease the apparent N concentration.
更好地理解溶质与奥氏体/铁素体界面之间的相互作用，有助于对奥氏体分解过程中铁素体生长进行建模，因为转变动力学受影响界面迁移率的溶质显著影响。在二元体系中，溶质与界面的相互作用主导着溶质在界面处的偏析，但在多组分合金中，溶质与溶质之间的相互作用也可能影响偏析。在本研究中，对Fe-Mn-N中的界面偏析进行了研究，并与Fe-Mn-C进行了比较，以揭示C对Mn偏析的影响程度。原子探针断层扫描（APT）非常适合分析界面处的溶质浓度，因为该技术兼具高空间分辨率和成分灵敏度。Mn的测量结果表明，仅在Fe-Mn-C中观察到偏析。这表明Mn的偏析主要是由对C的亲和力驱动的，C也会偏析到界面处。然而，用APT测量钢中的N可能会受到多种实验因素的影响。因此，在验证Fe-Mn-N的结果时，对脉冲方法（电压与激光）、样品制备（离子研磨与电解抛光）以及真空储存对测量的N浓度的影响进行了系统研究。观察到激光脉冲和聚焦离子束样品制备都会降低表观N浓度。
