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Severe Plastic Deformation (severe + plastic_deformation)
Selected AbstractsBulk Nanostructured Functional Materials By Severe Plastic Deformation,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Michael Zehetbauer Since severe plastic deformation (SPD) has demonstrated its capability of producing bulk nanomaterials with highly advanced mechanical properties, research is increasingly focusing on the question as to whether functional nanomaterials can be achieved by SPD and in bulk shape, too. This paper presents promising results of reaching functional properties in SPD-processed bulk nanocrystalline magnetic alloys, bulk shape memory nanoalloys, as well as nanometals and alloys for hydrogen storage, and also reports on problems with other functional properties, like those of thermoelectricity, occurring in non-metallic nanomaterials. [source] Optimization of the Magnetic Properties of FePd Alloys by Severe Plastic Deformation,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Abdelahad Chbihi Abstract A FePd alloy was nanostructured by severe plastic deformation following two different routes: ordered and disordered states were processed by high pressure torsion (HPT). A grain size in a range of 50 to 150,nm is obtained in both cases. Severe plastic deformation induces some significant disordering of the long range ordered L10 phase. However, transmission electron microscopy (TEM) data clearly show that few ordered nanocrystals remain in the deformed state. The deformed materials were annealed to achieve nanostructured long range ordered alloys. The transformation proceeds via a first order transition characterized by the nucleation of numerous ordered domains along grain boundaries. The influence of the annealing conditions (temperature and time) on the coercivity was studied for both routes. It is demonstrated that starting with the disorder state prior to HPT and annealing at low temperature (400,°C) leads to the highest coercivity (about 1.8,kOe). [source] Consolidation of Particles by Severe Plastic Deformation: Mechanism and Applications in Processing Bulk Ultrafine and Nanostructured Alloys and Composites,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Kenong Xia Severe plastic deformation (SPD) can be used to consolidate particles into bulk ultrafine and nanostructured materials. SPD consolidation relies on plastic deformation of individual particles, rather than diffusion, to achieve bonding and thus can be carried out at much lower temperatures. Using examples of consolidation of Al particles by back pressure equal channel angular pressing (BP-ECAP), it is demonstrated that full consolidation is achieved when the particles are sheared to disrupt the surface oxide layer whereas consolidation is impossible or incomplete in the case of particles sliding over each other. The effects of particle characteristics such as size, shape, strength and surface condition, as well as processing parameters including temperature and back pressure, are discussed to shed light on the mechanism of SPD consolidation. Potential applications of SPD in powder consolidation and processing of bulk ultrafine and nanostructured materials are discussed. [source] Enhanced Strength and Ductility of Ultrafine-Grained Ti Processed by Severe Plastic Deformation,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Irina Semenova This work deals with the study of strength and ductility in ultrafine-grained (UFG) Ti Grade 4 produced by equal channel angular pressing (ECAP) in combination with subsequent thermomechanical treatments. We found that additional annealing of UFG Ti resulted in unusual enhancement of strength and ductility, which is associated with not only small grain size but also with a grain boundary structure. The origin of this phenomenon is investigated using the results of transmission electron microscopy and atom probe tomography. The innovation potential of UFG Ti for medical use is considered. [source] A New Technique for Severe Plastic Deformation: The Cone,Cone MethodADVANCED ENGINEERING MATERIALS, Issue 12 2009Olivier Bouaziz Abstract A new technique for producing ultrafine grained materials by severe plastic deformation is proposed. The principle and possible design of this technique, referred to as "cone,cone method," are outlined and the first results of numerical simulations that demonstrate its feasibility are reported. These results give promise with regard to achieving very large plastic strains and the concomitant grain refinement in sheet products. [source] Commercialization of Nanostructured Metals Produced by Severe Plastic Deformation ProcessingADVANCED ENGINEERING MATERIALS, Issue 5 2003T.C. Lowe Abstract The promise of nanotechnology is increasingly being realized as governments, universities, public and private research laboratories, and the various industrial sectors devote resources to this emerging area. Estimates for the economic impact of nanotechnology on existing global markets exceed 700 billion by the year 2008. Nanomaterials are projected to be one of the earliest components of nanotechnology to appear in commercial applications. Amongst the emerging new nanomaterials, bulk nanostructured metals produced by severe plastic deformation (SPD) have shown promise in a wide range of application areas. In this paper, we overview developments in severe plastic deformation technology, emphasizing progress since the international workshop "Investigations and Applications of Severe Plastic Deformation" held 2,8 August 1999 in Moscow, Russia. Then, we overview some of principal areas of application for SPD metals and alloys. [source] Experimental Evidence for Grain-Boundary Sliding in Ultrafine-Grained Aluminum Processed by Severe Plastic Deformation,ADVANCED MATERIALS, Issue 1 2006Q. Chinh Evidence for grain boundary sliding in ultrafine-grained aluminum after processing with equal channel angular pressing (ECAP) is presented (see Figure). Pure aluminum is used as a model material; depth sensing indentation testing and atomic force microscopy are used to measure the nature of the displacements around indentations for samples in an annealed and work-hardened condition, and after processing using ECAP. [source] Bulk nanostructured titanium fabricated by hydrostatic extrusionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2010Krzysztof Topolski Abstract The paper is concerned with the use of Hydrostatic Extrusion (HE), which is one of the methods of Severe Plastic Deformation (SPD), for grain refinement of titanium grade 2. Titanium in the form of rods was subjected to multi-stage extrusion. The aim was to optimize the HE process so as to obtain nanostructured titanium rods. The results show that it is possible to produce nanostructured Ti rods of a diameter suitable for industrial applications. The refinement to nano-sized grains is accompanied by a significant improvement of mechanical properties. The tensile strength of more than 1000MPa was achieved and the hardness increase exceeded 50%. This study was also concerned with the problem of up-scaling the dimensions of nano-refined components produced by HE. The basic condition for HE to yield nanostructured Ti is that an appropriately high accumulated strain should be applied (, > 3). The results demonstrate that, by using HE, we can produce nano-Ti rods with diameters amounting to ,8mm. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optimization of the Magnetic Properties of FePd Alloys by Severe Plastic Deformation,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Abdelahad Chbihi Abstract A FePd alloy was nanostructured by severe plastic deformation following two different routes: ordered and disordered states were processed by high pressure torsion (HPT). A grain size in a range of 50 to 150,nm is obtained in both cases. Severe plastic deformation induces some significant disordering of the long range ordered L10 phase. However, transmission electron microscopy (TEM) data clearly show that few ordered nanocrystals remain in the deformed state. The deformed materials were annealed to achieve nanostructured long range ordered alloys. The transformation proceeds via a first order transition characterized by the nucleation of numerous ordered domains along grain boundaries. The influence of the annealing conditions (temperature and time) on the coercivity was studied for both routes. It is demonstrated that starting with the disorder state prior to HPT and annealing at low temperature (400,°C) leads to the highest coercivity (about 1.8,kOe). [source] Consolidation of Particles by Severe Plastic Deformation: Mechanism and Applications in Processing Bulk Ultrafine and Nanostructured Alloys and Composites,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Kenong Xia Severe plastic deformation (SPD) can be used to consolidate particles into bulk ultrafine and nanostructured materials. SPD consolidation relies on plastic deformation of individual particles, rather than diffusion, to achieve bonding and thus can be carried out at much lower temperatures. Using examples of consolidation of Al particles by back pressure equal channel angular pressing (BP-ECAP), it is demonstrated that full consolidation is achieved when the particles are sheared to disrupt the surface oxide layer whereas consolidation is impossible or incomplete in the case of particles sliding over each other. The effects of particle characteristics such as size, shape, strength and surface condition, as well as processing parameters including temperature and back pressure, are discussed to shed light on the mechanism of SPD consolidation. Potential applications of SPD in powder consolidation and processing of bulk ultrafine and nanostructured materials are discussed. [source] Suppression of Ni4Ti3 Precipitation by Grain Size Refinement in Ni-Rich NiTi Shape Memory Alloys,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Egor A. Prokofiev Severe plastic deformation (SPD) processes, such as equal channel angular pressing (ECAP) and high pressure torsion (HPT), are successfully employed to produce ultra fine grain (UFG) and nanocrystalline (NC) microstructures in a Ti,50.7,at% Ni shape memory alloy. The effect of grain size on subsequent Ni-rich particle precipitation during annealing is investigated by transmission electron microscopy (TEM), selected area electron diffraction (SAD, SAED), and X-ray diffraction (XRD). It is observed that Ni4Ti3 precipitation is suppressed in grains of cross-sectional equivalent diameter below approximately 150,nm, and that particle coarsening is inhibited by very fine grain sizes. The results suggest that fine grain sizes impede precipitation processes by disrupting the formation of self-accommodating particle arrays and that the arrays locally compensate for coherency strains during nucleation and growth. [source] Ultra-Fast Atomic Transport in Severely Deformed Materials,A Pathway to Applications?,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Sergiy Divinski Abstract Severe plastic deformation of pure Cu and Cu-rich alloys was found to create a hierarchical combination of fast and ultra-fast diffusion paths ranging from non-equilibrium grain boundaries to non-equilibrium triple junctions, vacancy clusters, nano- and micro-pores, and finally to general high-angle grain boundaries. Under certain conditions, a percolating network of porosity can be introduced in the ultra-fine grained materials by a proper mechanical and thermal treatment. This network may offer promising opportunities for creating materials with tailor-made properties, including combinations of improved mechanical performance with a possibility of self repair using "vascular structures" for atom transport. Applications in such areas as drug eluting bioimplants and lead or polymer eluting materials for reduction of friction based on impregnation of porosity networks with these agents are also envisaged. [source] Nanoscale Grain Refinement and H-Sorption Properties of MgH2 Processed by High-Pressure Torsion and Other Mechanical Routes,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Daniel Rodrigo Leiva MgH2 is a promising material for solid-state hydrogen storage due to its high gravimetric and volumetric storage capacity and its relatively low cost. Severe plastic deformation (SPD) processing techniques are being explored as an alternative to high-energy ball-milling (HEBM) in order to obtain more air resistant materials and reduce processing times. In this work, Mg, MgH2, and MgH2,Fe mixtures were severely mechanically processed by different techniques such as high-pressure torsion (HPT), extensive cold forging, and cold rolling. A very significant grain refinement was achieved when using MgH2 instead of Mg as raw material. The mean crystallite sizes observed ranged from 10 to 30,nm, depending on the processing conditions. Enhanced H-sorption properties were observed for the MgH2 -based nanocomposites processed by HPT when compared with MgH2 mixtures. Additionally, cold forging and cold rolling also proved effective in nanostructuring MgH2. These results suggest a high potential for innovative application with the use of low cost mechanical processing routes to produce Mg-based nanomaterials with attractive hydrogen storage properties. [source] The Art and Science of Tailoring Materials by Nanostructuring for Advanced Properties Using SPD Techniques,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Ruslan Z. Valiev In recent years a breakthrough has developed in the studies of nanostructured metals and alloys as advanced structural and functional materials associated both with the development of new routes for the fabrication of bulk nanostructured materials using severe plastic deformation (SPD) and with investigations of the fundamental mechanisms that lead to the new properties of these materials. This review paper discusses new concepts and principles in using SPD processing to fabricate bulk nanostructured metals with advanced properties. Special emphasis is placed on the relationship between microstructural features and properties, as well as the innovation potential of SPD-produced nanomaterials. [source] Bulk Nanostructured Functional Materials By Severe Plastic Deformation,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Michael Zehetbauer Since severe plastic deformation (SPD) has demonstrated its capability of producing bulk nanomaterials with highly advanced mechanical properties, research is increasingly focusing on the question as to whether functional nanomaterials can be achieved by SPD and in bulk shape, too. This paper presents promising results of reaching functional properties in SPD-processed bulk nanocrystalline magnetic alloys, bulk shape memory nanoalloys, as well as nanometals and alloys for hydrogen storage, and also reports on problems with other functional properties, like those of thermoelectricity, occurring in non-metallic nanomaterials. [source] New Routes for Fabricating Ultrafine-Grained Microstructures in Bulky Steels without Very-High Strains,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Nobuhiro Tsuji Abstract Several routes to produce ultrafine-grained structures in steels without severe plastic deformation are introduced. The key point of the ideas is to combine plastic deformation with the phase transformation of matrix phases. When as-quenched martensite in steels is used as a starting microstructure, sub-micrometer grain-sized structures can be obtained easily. Another example using a dual-phase steel composed of soft and hard phases is also discussed. Repeating plastic deformation and phase transformation is also effective in obtaining nanostructures in an austenitic stainless steel. Examples of strips of UFG stainless steels in industry and their applications are presented. [source] Optimization of the Magnetic Properties of FePd Alloys by Severe Plastic Deformation,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Abdelahad Chbihi Abstract A FePd alloy was nanostructured by severe plastic deformation following two different routes: ordered and disordered states were processed by high pressure torsion (HPT). A grain size in a range of 50 to 150,nm is obtained in both cases. Severe plastic deformation induces some significant disordering of the long range ordered L10 phase. However, transmission electron microscopy (TEM) data clearly show that few ordered nanocrystals remain in the deformed state. The deformed materials were annealed to achieve nanostructured long range ordered alloys. The transformation proceeds via a first order transition characterized by the nucleation of numerous ordered domains along grain boundaries. The influence of the annealing conditions (temperature and time) on the coercivity was studied for both routes. It is demonstrated that starting with the disorder state prior to HPT and annealing at low temperature (400,°C) leads to the highest coercivity (about 1.8,kOe). [source] Tailoring Materials Properties by Accumulative Roll Bonding,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Tina Hausöl Accumulative roll bonding (ARB) as a method of severe plastic deformation (SPD) is an interesting established process to produce ultrafine-grained (UFG) sheet materials with high potential for light weight constructions. The ARB process offers a high flexibility for tailored material design. Al2O3 particles, carbon fibers and titanium foils are used as reinforcement of aluminum sheets introduced during accumulative roll bonding. Furthermore multicomponent materials are produced by cladding of different aluminum alloys. These sandwich-like structures allow to combine desired properties of the materials involved. Post-ARB heat treatment offers another possibility for tailoring materials properties of graded structures as shown by formation of TiAl3 in Al/Ti laminates. The tailored materials are investigated by means of SEM, EDX, nanoindentation experiments and tensile testing. [source] Plasticity and Grain Boundary Diffusion at Small Grain Sizes,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Gerhard Wilde Bulk nanostructured,or ultrafine-grained materials are often fabricated by severe plastic deformation to break down the grain size by dislocation accumulation. Underlying the often spectacular property enhancement that forms the basis for a wide range of potential applications is a modification of the volume fraction of the grain boundaries. Yet, along with the property enhancements, several important questions arise concerning the accommodation of external stresses if dislocation-based processes are not longer dominant at small grain sizes. One question concerns so-called "non-equilibrium" grain boundaries that have been postulated to form during severe deformation and that might be of importance not only for the property enhancement known already today, but also for spectacular applications in the context of, e.g., gas permeation or fast matter transport for self-repairing structures. This contribution addresses the underlying issues by combining quantitative microstructure analysis at high resolution with grain boundary diffusion measurements. [source] A New Technique for Severe Plastic Deformation: The Cone,Cone MethodADVANCED ENGINEERING MATERIALS, Issue 12 2009Olivier Bouaziz Abstract A new technique for producing ultrafine grained materials by severe plastic deformation is proposed. The principle and possible design of this technique, referred to as "cone,cone method," are outlined and the first results of numerical simulations that demonstrate its feasibility are reported. These results give promise with regard to achieving very large plastic strains and the concomitant grain refinement in sheet products. [source] Microstructure and Mechanical Performance of Brand-New Al0.3CrFe1.5MnNi0.5 High-Entropy Alloys,ADVANCED ENGINEERING MATERIALS, Issue 10 2009Wei-Yeh Tang The microstructure, hardening behavior, and adhesive wear behavior of Al0.3CrFe1.5MnNi0.5 high-entropy alloys were investigated. All alloys exhibit superior adhesive wear resistance to cast iron FC-300, bearing steel SUJ-2, and hot-mold steel SKD-61. The superior wear resistance of the alloys is attributable to the formation of , phase during the furnace cooling from the homogenization at 1100 °C or the in situ formation of the ,phase induced by the high interface temperature and severe plastic deformation during wear sliding. [source] The Innovation Potential of Bulk Nanostructured MaterialsADVANCED ENGINEERING MATERIALS, Issue 7 2007Z. Valiev Abstract The innovation potential is high for bulk nanostructured materials (BNM) produced by methods of severe plastic deformation and accordingly this report focuses on very recent developments demonstrating the potential of using BNM for advanced and functional applications in engineering and medicine. [source] Commercialization of Nanostructured Metals Produced by Severe Plastic Deformation ProcessingADVANCED ENGINEERING MATERIALS, Issue 5 2003T.C. Lowe Abstract The promise of nanotechnology is increasingly being realized as governments, universities, public and private research laboratories, and the various industrial sectors devote resources to this emerging area. Estimates for the economic impact of nanotechnology on existing global markets exceed 700 billion by the year 2008. Nanomaterials are projected to be one of the earliest components of nanotechnology to appear in commercial applications. Amongst the emerging new nanomaterials, bulk nanostructured metals produced by severe plastic deformation (SPD) have shown promise in a wide range of application areas. In this paper, we overview developments in severe plastic deformation technology, emphasizing progress since the international workshop "Investigations and Applications of Severe Plastic Deformation" held 2,8 August 1999 in Moscow, Russia. Then, we overview some of principal areas of application for SPD metals and alloys. [source] Mechanical Behavior and Failure Analysis of Prosthetic Retaining Screws after Long-term Use In Vivo.JOURNAL OF PROSTHODONTICS, Issue 3 2008Part 1: Characterization of Adhesive Wear, Structure of Retaining Screws Abstract Purpose: The general aim of this study and those presented in Parts 2,4 of this series was to characterize the structure, properties, wear, and fracture of prosthetic retaining screws in fixed detachable hybrid prostheses after long-term use in vivo. This part of the overall investigation addresses whether there are differences in thread wear between the screws closest to the fulcrum and those that are farthest from the fulcrum in fixed detachable hybrid prostheses. Materials and Methods: The total number of prosthetic retaining screws used in this study was 100 (10 new and 90 used). New screws (controls) from Nobel Biocare (NB) were divided into Group 1 (slotted) and Group 2 (hexed). Ninety used screws (in service 18,120 months) were retrieved from fixed detachable hybrid prostheses in 18 patients (5 screws from each patient, 60 from NB and 30 from Sterngold). The used screws were divided into 18 groups. Additionally, each group was subdivided into A and B categories. Category A contained the middle three prosthetic screws, which were considered the farthest screws from the fulcrum line. Category B contained the most posterior two screws, which were considered the screws closest to the fulcrum line. All 100 screws were subjected to thorough, nondestructive testing. Results: Light and scanning electron microscopic examination of all used screws for each group revealed surface deterioration of the active profile of the screw threads consistent with adhesive wear. The observed thread profile deterioration ranged from mild to severe. The wear was aggressive enough to cause galling, which led to thinning of the threads and, in severe cases, to knife-edges at thread crests. In ten groups, the most anterior three screws exhibited more wear than the most posterior two screws. In addition to thread wear, severe plastic deformation was detected on the bottom part of each screw for three groups, and a long external longitudinal crack was detected in one screw of Group 2. Conclusions: The findings of this study and those presented in Parts 2,4 demonstrate that different retaining screws from the same manufacturer and/or from different manufacturers have different geometrical design, microstructures, major alloy constituents, and microhardness, and that these differences influence their preload and fractured load values. In this part of the overall investigation, the occurrence of galling as a result of wear involving prosthetic retaining screws appears to be an inevitable and unavoidable consequence of long-term use in vivo in fixed detachable hybrid prostheses regardless of the intended/original preload value. The galling rate is greater on the middle three screws compared to the most posterior two screws in fixed detachable hybrid prostheses. The wear pattern is consistent with an adhesive wear mechanism; however, this study does not provide enough data to support a definitive analysis. [source] Strain rate sensitivity of Cu after severe plastic deformation by multiple compressionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2005Y. J. Li Abstract Coarse-grained Cu99.99 was prestrained by ,pre in multiple compression in three orthogonal directions at room temperature. While the flow stress , saturates at ,pre , 2, the strain rate sensitivity of , at 318 K increases by a factor of , 2.7 from ,pre = 2 to 7. This increase is attributed to decrease of grain size and corresponding increase in fraction of high-angle grain boundaries. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Autonomous damage initiated healing in a thermo-responsive ionomerPOLYMER INTERNATIONAL, Issue 8 2010Russell John Varley Abstract The partially neutralised poly[ethylene- co -(methacrylic acid)] copolymer Surlyn 8940® (DuPont) ionomer exhibits damage-initiated healing during high-energy impact. This is attributed to the hierarchical structure of ionomers, arising from the presence of ionic aggregates and hydrogen bonding. This work investigates the mechanism of this process using novel techniques developed here. The ionomer's response to penetration has been found to consist of three consecutive events: an initial elastic response, an anelastic response and pseudo-brittle failure. In addition, the ultimate level of healing has been shown to be dependent upon the elastic response during impact as well as post-failure viscous flow. Increasing the local temperature at impact consistently increases elastic healing, although further improvements in healing are minor once the local temperature increases beyond the melting point. Below the order-to-disorder transition, microscopic investigations reveal severe plastic deformation while the lack of shape memory reduces the comparative level of elastic healing. Above this temperature, healing is facilitated by elastomeric behaviour at the impact site, while above the melting point a combination of elastomeric and viscous flow dominates. This work provides for the first time evidence of the consecutive healing events occurring during high-impact penetration for ionomers. The hierarchical structure of ionomers and its impact upon the microstructure have been shown to be critical to the process. Comparison of the mechanical response during impact with that of non-ionic polymers further highlights this. In addition, slow relaxational processes occurring post-impact are found to facilitate further recovery in mechanical properties. Copyright © 2010 Society of Chemical Industry [source] | |||||||||||||