An investigation of surface nanocrystallization mechanism in Fe induced by surface mechanical attrition treatment

By means of surface mechanical attrition (SMA), a nanostructured surface layer was formed on a pure Fe plate. Microstructure features of various sections in the surface layer, from the strain-free matrix to the treated top surface, were systematically characterized by using X-ray diffraction (XRD) a...

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Bibliographic Details
Published in:Acta materialia 2002-10, Vol.50 (18), p.4603-4616
Main Authors: Tao, N.R., Wang, Z.B., Tong, W.P., Sui, M.L., Lu, J., Lu, K.
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Grain refinement
Iron
Metals. Metallurgy
Microstructure
Nanocrystalline materials
Other surface treatments
Production techniques
Surface treatment
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Summary:By means of surface mechanical attrition (SMA), a nanostructured surface layer was formed on a pure Fe plate. Microstructure features of various sections in the surface layer, from the strain-free matrix to the treated top surface, were systematically characterized by using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. Based on the experimental observations, a grain refinement mechanism induced by plastic deformation during the SMA treatment in Fe was proposed. It involves formation of dense dislocation walls (DDWs) and dislocation tangles (DTs) in original grains and in the refined cells (under further straining) as well, transformation of DDWs and DTs into subboundaries with small misorientations separating individual cells or subgrains, and evolution of subboundaries to highly misoriented grain boundaries. Experimental evidences and analysis of the grain refinement mechanism indicate that high strains with a high strain rate are necessary for formation of nanocrystallites during plastic deformation of metals.
ISSN:1359-6454
1873-2453
DOI:10.1016/S1359-6454(02)00310-5