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Journal ArticleDOI

Microstructure and evolution of mechanically-induced ultrafine grain in surface layer of AL-alloy subjected to USSP

08 May 2002-Acta Materialia (Pergamon)-Vol. 50, Iss: 8, pp 2075-2084
TL;DR: In this paper, the authors investigated the UFG microstructures in the surface layer of an aluminum alloy 7075 heavily worked by ultrasonic shot peening and found that the grain subdivision into the subgrains was the main mechanism responsible for grain refinement.
About: This article is published in Acta Materialia.The article was published on 2002-05-08 and is currently open access. It has received 418 citations till now. The article focuses on the topics: Dislocation & Surface layer.
Citations
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Journal ArticleDOI
TL;DR: In this article, a surface mechanical attrition treatment (SMAT) was developed for synthesizing a nanostructured surface layer on metallic materials in order to upgrade the overall properties and performance.
Abstract: In terms of the grain refinement mechanism induced by plastic straining, a novel surface mechanical attrition treatment (SMAT) was developed for synthesizing a nanostructured surface layer on metallic materials in order to upgrade the overall properties and performance. In this paper, the SMAT technique and the microstructure of the SMAT surface layer will be described. The grain refinement mechanism of the surface layer during the SMAT will be analyzed in terms of the microstructure observations in several typical materials. Obvious enhancements in mechanical properties and tribological properties of the nanostructured surface layer in different materials were observed. Further development and prospects will be addressed with respect to the SMAT as well as the performance and technological applications of the engineering materials with the nanostructured surface layer.

910 citations

Journal ArticleDOI
TL;DR: In this paper, a nanostructured surface layer was formed on an AISI 304 stainless steel with low stacking-fault energy by means of the surface mechanical attrition treatment (SMAT).

604 citations

Journal ArticleDOI
TL;DR: In this article, two different mechanisms for plastic strain-induced grain refinement in pure Cu were identified, corresponding to different levels of strain rate, and the minimum size of refined grains via this process is about 100 nm.

446 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of a nanocrystalline surface layer on the fatigue behavior of a 316L stainless steel is investigated, and significant enhancements of the yield stress and the fatigue limit have been achieved through surface mechanical attrition treatment (SMAT).

435 citations

Journal ArticleDOI
TL;DR: In this paper, a nanostructured surface layer up to 50 μm thick was produced on commercially pure titanium using surface mechanical attrition treatment (SMAT), and the microstructural features of the surface layer produced by SMAT were systematically characterized by cross-sectional optical microscopy observations, transmission electron microscopy (TEM) and high-resolution transmission electron microscope (HRTEM) investigations.

424 citations

References
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Journal ArticleDOI
TL;DR: In this article, experiments were conducted on high purity aluminum to investigate the process of grain refinement during equal-channel angular (ECA) pressing, where samples were subjected to 1 to 4 pressings and then sectioned for microstructural examination in three mutually perpendicular directions.

1,135 citations

Journal ArticleDOI
TL;DR: In this article, the formation of a special grain boundary phase, i.e., a thin near-boundary layer with high dynamic activity of atoms, has been found, leading to the manifestation of promising new elastic, strength, superplastic, damping and magnetic properties of UFG materials.
Abstract: Strain-heat methods of obtaining ultrafine-grained (UFG) metallic materials with grain sizes as small as 20 nm and peculiarities of their structure are considered. It is shown that intercrystalline boundaries are the main element of the structure of UFG materials and that they are typically in a non-equilibrium state. The formation of a special grain boundary phase, i.e. a thin near-boundary layer with high dynamic activity of atoms, has been found. This unusual structure leads to the manifestation of promising new elastic, strength, superplastic, damping and magnetic properties of UFG materials.

918 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the microstructural evolution during polyslip in f.c.m.d. metals and showed that there are differences in the number and selection of simultaneously acting slip systems among neighboring volume elements of individual grains.
Abstract: The microstructural evolution during polyslip in f.c.c. metals in investigated by the examples of Al, Ni, NiCo alloys and an AlMg alloy, deformed at room temperature either by rolling or by torsion. The principles governing this evolution appears to be the following: (a) There are differences in the number and selection of simultaneously acting slip systems among neighboring volume elements of individual grains. In any one volume element (called a cell block), the number of slip systems falls short of that required for homogeneous (Taylor) deformation, but groups of neighboring cell blocks fulfil the Taylor criterion collectively. (b) The dislocations are trapped into low-energy dislocation structures in which neigboring dislocations mutually screen their stresses. The microstructural evolution at small strains progresses by the subdivision of grains into cell blocks delineated by dislocation boundaries. These boundaries accomodate the lattice misorientations, which result from glide on different slip system combinations in neighbouring cell blocks. The cell blocks are subdivided into ordinary cells and both cell blocks and cells shrink with increasing strain. All observations appear to be in good accord with the theoretical interpretation. However, some problems remain to be solved quantitatively.

789 citations

Journal ArticleDOI
TL;DR: In this article, the development of an ultra-fine grain size during equal-channel angular (ECA) pressing of high purity aluminum with an initial grain size of ∼1.0 mm was investigated.

759 citations