Modeling nitriding enhancement resulting from the NanoPeening treatment of a Pure Iron

6th International Conference on Nanomaterials by Severe Plastic Deformation

材料科学;化学

Lacaille, V.^1,2,3 ; Kermouche, G.^3 ; Spinel, D.-Y. Tumbajoy^3 ; Feulvarch, E.^2 ; Morel, C.^1 ; Bergheau, J.-M.^2

Winoa, 528 avenue de Savoie, 38570 Le Cheylas, France^1

Université de Lyon, ENISE, UMR 5513 CNRS, 58 rue Jean Parot, 42023 Saint-Étienne Cedex 2, France^2

École des Mines de Saint-Etienne, Science of Materials and Structures (SMS) Division, LGF UMR 5307 CNRS, 158 Cours Fauriel, 42023 Saint-Etienne, France^3

关键词: Concentration profiles;    Enhanced diffusion;    Finite element simulations;    Grain boundary densities;    Grain size distribution;    Nano-structured layer;    Nitrogen diffusion;    Optical micrography;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/63/1/012124/pdf
DOI  :  10.1088/1757-899X/63/1/012124

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Nanocrystalline materials are well known to have enhanced diffusion properties, especially due to their high grain boundary density which are fast diffusion channels in the material. In this paper, a highly pure iron sample is treated by Nano Peening® to obtain a nanostructured layer with nanometric grains in the top surface. Then, the grain size distribution is measured by EBSD and optical micrography to fit with an analytical law. It is shown that an exponential law is a good estimator for the grain size distribution after Nano Peening®. Then, using this grain size distribution, the diffusivity distribution is calculated with an analytical model we recently proposed. A 1D finite element simulation of nitrogen diffusion is then performed with this distribution and the concentration profiles are compared with those extracted from a simulation with a constant grain size distribution. Simulations show that Nano Peening® significantly enhances diffusion, dividing the nitriding duration by 2 or by obtaining a 120% gain in the nitriding depth.