Prediction of solute concentration gradients during growth of discontinuous precipitates in a Fe-13.5 at.% Zn alloy

• Published in: Materials letters 2021-10, Vol.301, p.130317, Article 130317
• Main Authors: Chronowski, Mateusz, Opara, Jarosław, Kogtenkova, Olga A., Druzhinin, Alexander V., Zięba, Paweł
• Format: Article
• Language: English
• Subjects: Cellular precipitates; Chemical precipitation; Concentration gradient; Diffusion; Interfaces; Lamella; Materials science; Phase transformations; Precipitates; Solute concentration gradient; Thickness; Zinc base alloys
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2021.130317

•The go- and stop- type of RF movement during DP in Fe-13.5 at.% Zn alloy.•Go- and stop- motion is reflected by appropriate changes of C parameter.•Changes of Zn gradient in α lamella during the stop- period were described. The influence of Zn-concentration gradient on the occurrence of discontinuous precipitation has been analyzed in a Fe-13.5 at.% Zn alloy using the simulation method and Cahn′s diffusion model. The results have shown that the reaction front (RF) movement takes place by go- and -stop fashion accompanied by appropriate changes of Cahn′s parameter reaching maximum values, Cmax at the end of go- period. Then, the value of C decreases enabling relaxation of the RF and beginning of the next go- event. In this way, the simulation is the only one source of data showing how the solute concentration across the α phase lamella changes during the stop- period of the growth of discontinuous precipitates. The smaller thickness of the α phase lamellae and larger Cmax, the longer whole go- and –stop cycle, but not exceeding few seconds. The distance of RF movement is characterized by certain optimum value which is close to v = 45 nm/s regardless of the value of α phase lamella thickness.