共查询到20条相似文献,搜索用时 468 毫秒
1.
R.Z. Valiev 《Advanced Engineering Materials》2003,5(5):296-300
Severe plastic deformation (SPD) can lead to emergence of microstructural features and properties in materials which are fundamentally different from the ones well known for conventional cold deformation. In particular, the instances of unusual phase transformations resulting in development of highly metastable states associated with formation of supersaturated solid solutions, disordering or amorphization and their further decomposition during heating, high thermal stability of the SPD‐produced nanostructures, and the paradox of strength and ductility in some SPD‐processed metals and alloys are discussed. 相似文献
2.
ARB (Accumulative Roll‐Bonding) and other new Techniques to Produce Bulk Ultrafine Grained Materials
Accumulative roll‐Bonding (ARB) is a severe plastic deformation (SPD) process invented by the authors in order to fabricate ultrafine grained metallic materials. ARB is the only SPD process applicable to continuous production of bulky materials. In the process, 50 % rolled material is cut into two, stacked to be the initial dimension and then rolled again. In order to obtain one‐body solid material, the rolling in ARB is not only a deformation process but also a bonding process (roll‐bonding). By repeating this procedure, SPD of bulky materials can be realized. In this review paper, various kinds of new SPD mechanical properties of the ARB processed materials are indicated. 相似文献
3.
Ruslan Z. Valiev Maxim Yu. Murashkin Askar Kilmametov Boris Straumal Nguyen Q. Chinh Terence G. Langdon 《Journal of Materials Science》2010,45(17):4718-4724
Processing by severe plastic deformation (SPD) typically increases the strength of metals and alloys drastically by decreasing
their grain size into the submicrometer or nanometer range but the ductility of such materials remains typically low. This
report describes the first demonstration that it is possible to increase the room temperature ductility of aluminum-based
alloys processed by SPD and to attain elongations to failure of >150% while retaining the enhanced strength. This unique combination
of properties is due to the occurrence of grain boundary sliding at room temperature. The sliding was obviously achieved by
introducing a grain boundary wetting of the aluminum/aluminum grain boundaries. 相似文献
4.
P. Luo H. Xie M. Paladugu S. Palanisamy M. S. Dargusch K. Xia 《Journal of Materials Science》2010,45(17):4606-4612
It has been demonstrated that severe plastic deformation (SPD) can be used to consolidate particles of a wide range of sizes
from nano to micro into fully dense bulk material with good mechanical properties. SPD consolidation allows processing to
be conducted at much lower temperatures and is therefore suitable for particles with highly metastable structures such as
nanocrystalline. It is especially useful in the fabrication of multiphase materials including metal matrix nanocomposites.
In this investigation, SPD consolidation was applied to recycle Ti machining chips. In particular, the as-received chips were
consolidated by equal channel angular pressing at temperatures between 400 and 600 °C with the application of a back pressure
from 50 to 200 MPa. Fully dense bulk Ti with fine grain sizes was produced, possessing strength comparable or higher than
that of commercially pure wrought Ti. It is concluded that SPD consolidation is a promising method for recycling and value-adding
of Ti chips. 相似文献
5.
In this brief communication, we would like to review present data on fatigue performance of ultra‐fine grain materials fabricated by severe plastic deformation (SPD) and to discuss the possible mechanisms of their plastic deformation and degradation in light of currently available experimental data. The most prominent effect of SPD is often associated with significant grain refinement down to the nanoscopic scale. The other evident effect, which accompanies intensive plastic straining, is the dislocation accumulation up to limiting densities of 1016 m–2. Since namely these two factors, the grain size and the dislocation density, govern the strengthening of polycrystalline materials, we shall primarily confine ourselves to their role in cyclic deformation of severely pre‐deformed metals. 相似文献
6.
Yi Huang Roberto B. Figueiredo Thierry Baudin Anne-Laure Helbert Fran?ois Brisset Terence G. Langdon 《Journal of Materials Science》2012,47(22):7796-7806
It is now well known that processing by SPD can significantly increase the strength of metallic materials by refining the grain structure and increasing the density of defects. The rapid increase in strength observed in the early stages of deformation is expected to slow down and saturate at large strains because of an increasing recovery of the material. Therefore, a saturation strength is anticipated that will depend on the processing temperature. This investigation analyses this parameter by determining the evolution of hardness of a magnesium alloy processed by high-pressure torsion at different temperatures. 相似文献
7.
Nong Gao Chuan Ting Wang Robert J. K. Wood Terence G. Langdon 《Journal of Materials Science》2012,47(12):4779-4797
Processing by severe plastic deformation (SPD) has been developed extensively over the last two decades in order to produce
ultrafine-grained (UFG) materials having submicrometre or nanometre grain sizes. An important material property for UFG materials
is good wear resistance so that they may be used in a range of structural applications. An examination of the published data
shows that only limited reports are available to date on the wear behaviour of SPD-processed materials and, furthermore, many
of these results appear to be conflicting. The correlation of hardness and wear is limited because the wear property is a
system property that in practice is influenced by a range of factors. Accordingly, this review is designed to examine recent
reports related to the wear resistance of materials processed by SPD with particular emphasis on alloys processed using equal-channel
angular pressing (ECAP), high-pressure torsion (HPT) and accumulative roll-bonding (ARB). 相似文献
8.
Kim TN Balakrishnan A Lee BC Kim WS Dvorankova B Smetana K Park JK Panigrahi BB 《Journal of materials science. Materials in medicine》2008,19(2):553-557
The in vitro response of the mouse fibroblast cell line 3T3 on the surface of ultrafine grained titanium [produced by a severe
plastic deformation (SPD) process] has been studied in this work. SPD Ti showed much higher strength than the coarse grained
Ti and equivalent to that of Ti–6Al–4V alloy. Better cell proliferation was observed on SPD Ti compared to conventional Ti
and Ti–6Al–4V alloy. This could be attributed to the increased surface free energy by reduction in the grain size and possibly
the presence of a large number of nano size grooves at the triple point junctions in SPD Ti sample. There was no significant
difference in the results of cytotoxicity tests of fine and coarse grained materials. 相似文献
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10.
Maximilien E. Launey Robert O. Ritchie 《Advanced materials (Deerfield Beach, Fla.)》2009,21(20):2103-2110
Few engineering materials are limited by their strength; rather they are limited by their resistance to fracture or fracture toughness. It is not by accident that most critical structures, such as bridges, ships, nuclear pressure vessels and so forth, are manufactured from materials that are comparatively low in strength but high in toughness. Indeed, in many classes of materials, strength and toughness are almost mutually exclusive. From a fracture‐mechanics perspective, the ability of a microstructure to develop toughening mechanisms acting either ahead or behind the crack tip can result in resistance‐curve (R‐curve) behavior where the fracture resistance actually increases with crack extension; the implication here is that toughness is often developed primarily during crack growth and not for crack initiation. Biological materials are perfect examples of this; moreover, they offer microstructural design strategies for the development of new materials for structural applications demanding combinations of both strength and toughness. 相似文献
11.
Malgorzata Lewandowska Krzysztof J. Kurzydlowski 《Journal of Materials Science》2010,45(17):4877-4883
The article describes the combined effects of grain size and second phase particles on mechanical properties of CuCrZr alloy
subjected to SPD processing and ageing in two sequences: (i) SPD processing followed by ageing and (ii) SPD processing of
samples aged prior to deformation. It was revealed that each of these strengthening mechanisms acting alone gives a significant
increase in mechanical strength (5 and 10 times in the case of ageing and SPD processing, respectively). However, it has been
found in the present study that the strength of samples subjected to grain refinement and precipitation hardening is not a
direct sum of the strengthening brought about by these two strengthening mechanisms acting alone. This finding is discussed
in terms of the inter-dependence of grain size–particle strengthening in SPD nano-metals. 相似文献
12.
Review of principles and methods of severe plastic deformation for producing ultrafine-grained tubes
Severe plastic deformation (SPD) is known to be the best method for producing bulk ultrafine-grained and nanostructured materials with excellent properties. Different SPD methods were developed that are suitable for sheet and bulk solid materials. During the past decade, efforts have been made to create effective SPD processes suitable for producing cylindrical tubes. In this paper, we review SPD processes intended to produce ultrafine-grained and nanostructured tubes, and their effects on material properties. The paper will focus on introduction of the tube SPD processes, and then comparison of them based on their advantages and disadvantages from the viewpoints of processing and properties. 相似文献
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16.
Recent development in grain refinement by hydrostatic extrusion 总被引:1,自引:1,他引:0
Malgorzata Lewandowska Krzysztof J. Kurzydlowski 《Journal of Materials Science》2008,43(23-24):7299-7306
Hydrostatic extrusion is an efficient method of grain refinement to the nanometer scale in metallic materials. The paper shows that it can be used directly to obtain a mean grain size smaller than 100 nm with a significant fraction of high angle grain boundaries in aluminum alloys, titanium, and iron. It is also demonstrated that grain size reduction to this level in some other materials, e.g., nickel, requires a combination of hydrostatic extrusion (HE), as the final operation, after some other methods of severe plastic deformation (SPD). Grain refinement in metallic materials by HE has a significant effect on their properties with a significant increase in mechanical strength and improvement of wear and corrosion resistance while maintaining an acceptable level of plasticity. 相似文献
17.
R. Z. Valiev 《Journal of Materials Science》2007,42(5):1483-1490
During the past decade, fabrication of bulk nanostructured metals and alloys using severe plastic deformation (SPD) has been
evolving as a rapidly advancing direction of nanomaterials science and technology aimed at developing materials with new mechanical
and functional properties for advanced applications. The principle of these developments is based on grain refinement down
to the nanoscale level via various SPD techniques. This paper is focused on investigation and development of new SPD processing
routes enabling fabrication of fully dense bulk nanostructured metals and alloys with a grain size of 40–50 nm and smaller,
namely, SPD-consolidation of powders, including nanostructured ones, as well as SPD-induced nanocrystallization of amorphous
alloys. We also consider microstructural features of SPD-processed materials that are responsible for enhancement of their
properties. 相似文献
18.
《Materials Science & Technology》2013,29(2):119-126
AbstractThis paper reviews research work at the Institute for Materials and Advanced Processes, University of Idaho, on the synthesis of nanocrystalline materials and their consolidation. Nanocrystalline materials have been synthesised by a number of ‘far from equilibrium’ processes including mechanical alloying (MA), mechanochemical processing (MCP), supercritical fluid processing (SCFP), and severe plastic deformation (SPD). Examples of the materials include the TiAl based intermetallic compounds and composites produced by MA and SPD, Ti base alloys and metal carbides synthesised by MCP, thin film Cu produced by SCFP, and Al–Fe alloys produced by SPD. Details of the processes used and the enhancement of properties owing to the nanoscale structures in consolidated material will be presented. The potential of these processes to substitute for conventional methods of production will also be discussed. 相似文献
19.
The focus of this article is texture development in metals of fcc, bcc, and hcp crystal structure processed by a severe plastic deformation (SPD) technique called equal-channel angular extrusion (ECAE) or equal-channel angular pressing (ECAP). The ECAE process involves very large plastic strains and is well known for its ability to refine the grain size of a polycrystalline metal to submicron or even nano-size lengthscales depending on the material. During this process, the texture also changes substantially. While the strength, microstructure and formability of ECAE-deformed metals have received much attention, texture evolution and its connection with these properties have not. In this article, we cover a multitude of factors that can influence texture evolution, such as applied strain path, die geometry, processing conditions, deformation inhomogeneities, accumulated strain, crystal structure, material plastic behavior, initial texture, dynamic recrystallization, substructure, and deformation twinning. We evaluate current constitutive models for texture evolution based on the physics they include and their agreement with measurements. Last, we discuss the influence of texture on post-processed mechanical response, plastic anisotropy, and grain refinement, properties which have made ECAE, as well as other SPD processes, attractive. It is our intent to make SPD researchers aware of the importance of texture development in SPD and provide the background, guidance, and methodologies necessary for incorporating texture analyses in their studies. 相似文献