Available online at www.sciencedirect.com d Scripta MATERIALIA ELSEVIER Scripta Materialia 51 (2004)825-830 www.actamat-journals.com Performance and applications of nanostructured materials produced by severe plastic deformation Yuntian T.Zhua",Terry C.Lowe Terence G.Langdonb Los Alamos National Laboratory,Materials Science:Technology Division.MS G755,Los Alamos.NM 87545.USA bDepartments of Aerospace Mechanical Engineering and Materials Science,University of Southern California.Los Angeles.CA90089-1453.USA Accepted 4 May 2004 Available online 4 June 2004 Abstract Nanostructured materials produced by severe plastic deformation can be tailored to have both superior performance and superior properties.These materials are attractive for use in a range of applications from biomedical to aerospace industries. 2004 Acta Materialia Inc.Published by Elsevier Ltd.All rights reserved. Keywords:Applications;Manufacturing:Nanostructured materials;Severe plastic deformation 1.Introduction tion domains(crystallites),which are often smaller than 100 nm.Therefore,they can be called NS materials [5]. Nanostructured (NS)materials are defined as solids Several SPD processing methods are now available, having microstructural features in the range of ~1-100 including equal-channel angular pressing(ECAP)[6,7], nm in at least one dimension [1.Two complementary high-pressure torsion [5,8],accumulative roll-bonding approaches have been developed in attempts to synthe- (ARB)[9,10],repetitive corrugation and straightening size NS solids.The first is the "bottom-up"approach in [11,12],and friction stir processing (FSP)[13,14].At- which bulk NS materials are assembled from individual tempts have also been made to combine some of these atoms or from nanoscale building blocks such as nano- procedures such as ECAP and cold rolling [15],ARB particles.Techniques in this category include inert gas and FSP [16]or ECAP and HPT [17,18].An overall condensation [2],electrodeposition [3],and chemical and review of these various techniques suggests that,at least physical deposition [4]. in terms of the commercial viability of the processing The second approach is the "top-down"approach in route and the nature of the microstructures attained to which existing coarse-grained materials are processed to date,processing by ECAP has at least two advantages produce substantial grain refinement and a nanostruc- that favor its adoption into manufacturing practice. ture.The most successful "top-down"approach in- Firstly,it can be scaled up to produce relatively large volves the use of severe plastic deformation (SPD) bulk samples [19,20].Secondly,several groups have processing in which materials are subjected to the incorporated it into conventional rolling mills for con- imposition of very large strains without the introduction tinuous processing [21-23]. of concomitant changes in the cross-sectional dimen- Processing through the use of SPD techniques pro- sions of the samples.Materials produced by SPD tech- vides the capability of producing large,bulk NS mate- niques usually have grain sizes in the range of 100-1000 rials that may be utilized in structural applications.The nm.However,they have subgrain structures,such as incorporation of ECAP into continuous production subgrains,dislocation cells and X-ray coherent diffrac- techniques also holds out the promise of producing NS materials with a competitive low cost.Current costs to produce 5-20 mm diameter round bar of NS titanium "Corresponding author.Tel:+1-505-667-4029:fax:+1-505-667- and titanium alloys by non-continuous ECAP range 2264. between S50 and $150/kg.These costs are comparable to E-mail address:yzhu@lanlgov (Y.T.Zhu). those for intensive thermomechanical size reductions of 1359-6462/S-see front matter 2004 Acta Materialia Inc.Published by Elsevier Ltd.All rights reserved. doi:10.1016/j.scriptamat.2004.05.006Performance and applications of nanostructured materials produced by severe plastic deformation Yuntian T. Zhu a,*, Terry C. Lowe a , Terence G. Langdon b a Los Alamos National Laboratory, Materials Science; Technology Division, MS G755, Los Alamos, NM 87545, USA b Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453, USA Accepted 4 May 2004 Available online 4 June 2004 Abstract Nanostructured materials produced by severe plastic deformation can be tailored to have both superior performance and superior properties. These materials are attractive for use in a range of applications from biomedical to aerospace industries.
2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Applications; Manufacturing; Nanostructured materials; Severe plastic deformation 1. Introduction Nanostructured (NS) materials are defined as solids having microstructural features in the range of
1–100 nm in at least one dimension [1]. Two complementary approaches have been developed in attempts to synthe￾size NS solids. The first is the ‘‘bottom–up’’ approach in which bulk NS materials are assembled from individual atoms or from nanoscale building blocks such as nano￾particles. Techniques in this category include inert gas condensation [2], electrodeposition [3], and chemical and physical deposition [4]. The second approach is the ‘‘top–down’’ approach in which existing coarse-grained materials are processed to produce substantial grain refinement and a nanostruc￾ture. The most successful ‘‘top–down’’ approach in￾volves the use of severe plastic deformation (SPD) processing in which materials are subjected to the imposition of very large strains without the introduction of concomitant changes in the cross-sectional dimen￾sions of the samples. Materials produced by SPD tech￾niques usually have grain sizes in the range of 100–1000 nm. However, they have subgrain structures, such as subgrains, dislocation cells and X-ray coherent diffrac￾tion domains (crystallites), which are often smaller than 100 nm. Therefore, they can be called NS materials [5]. Several SPD processing methods are now available, including equal-channel angular pressing (ECAP) [6,7], high-pressure torsion [5,8], accumulative roll-bonding (ARB) [9,10], repetitive corrugation and straightening [11,12], and friction stir processing (FSP) [13,14]. At￾tempts have also been made to combine some of these procedures such as ECAP and cold rolling [15], ARB and FSP [16] or ECAP and HPT [17,18]. An overall review of these various techniques suggests that, at least in terms of the commercial viability of the processing route and the nature of the microstructures attained to date, processing by ECAP has at least two advantages that favor its adoption into manufacturing practice. Firstly, it can be scaled up to produce relatively large bulk samples [19,20]. Secondly, several groups have incorporated it into conventional rolling mills for con￾tinuous processing [21–23]. Processing through the use of SPD techniques pro￾vides the capability of producing large, bulk NS mate￾rials that may be utilized in structural applications. The incorporation of ECAP into continuous production techniques also holds out the promise of producing NS materials with a competitive low cost. Current costs to produce 5–20 mm diameter round bar of NS titanium and titanium alloys by non-continuous ECAP range between $50 and $150/kg. These costs are comparable to those for intensive thermomechanical size reductions of * Corresponding author. Tel.: +1-505-667-4029; fax: +1-505-667- 2264. E-mail address: yzhu@lanl.gov (Y.T. Zhu). 1359-6462/$ - see front matter
2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.scriptamat.2004.05.006 Scripta Materialia 51 (2004) 825–830 www.actamat-journals.com