ČERMÁK Jiří Institute of Physics of Materials, v.v.i. AS CR

Spoluautoři KRÁL Lubomír

Carbon diffusion was studied in temperature interval 573 - 1073 K in carbon-supersaturated surface layer of 9Cr–1Mo steel P91 and in model Fe-15Cr binary alloy. Extremely low carbon diffusion coefficient D (by 3 orders of magnitude lower than the value Deq in material with equilibrium carbon concentration) was observed in carburized surface region of Fe-15Cr. Similar results were obtained for P91 above the temperature Tn ~ 800 K. However, below Tn, the values of D measured in P91 increased and approached the value of Deq. It seems that the non-Arrhenius behaviour of P91 steel around Tn may be ascribed to the α → α + α’ phase decomposition. Possible effect of nitrogen upon the low-temperature increase in D in P91 steel was excluded.

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