Microstructure Development and Superplasticity in a Zn-22% Al Eutectoid Alloy Processed by Severe Plastic Deformation

2014 ◽  
Vol 783-786 ◽  
pp. 2647-2652 ◽  
Author(s):  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Ultrafine Grain ◽  
Al Alloy ◽  
Grain Sizes ◽  
Angular Pressing ◽  
Flow Mechanisms ◽  
Superplastic Properties ◽  
Eutectoid Alloy

Severe plastic deformation (SPD) is an attractive processing method for refining microstructures to have ultrafine grain sizes within the submicrometer or even the nanometer levels. In SPD, the most promising techniques are equal-channel angular pressing (ECAP) and high-pressure torsion (HPT). A conventional superplastic Zn-22% Al eutectoid alloy was processed by ECAP and HPT. Experiments were conducted to demonstrate the evolution of hardness and microstructure and the enhancement of superplastic properties of the Zn-Al alloy after processing by the SPD techniques. In addition, flow mechanisms of the Zn-22% Al alloy are discussed by utilizing a deformation mechanism map.

Processing of Aluminium Alloys by Severe Plastic Deformation

2006 ◽  
Vol 519-521 ◽  
pp. 45-54 ◽  
Author(s):  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Elevated Temperatures ◽  
High Pressure Torsion ◽  
Simple Procedure ◽  
Superplastic Forming ◽  
High Strength ◽  
Ultrafine Grain ◽  
Grain Sizes

Processing through the application of severe plastic deformation (SPD) has become important over the last decade because it is now recognized that it provides a simple procedure for producing fully-dense bulk metals with grain sizes lying typically in the submicrometer range. There are two major procedures for SPD processing. First, equal-channel angular pressing (ECAP) refers to the repetitive pressing of a metal bar or rod through a die where the sample is constrained within a channel bent through an abrupt angle at, or close to, 90 degrees. Second, high-pressure torsion (HPT) refers to the procedure in which the sample, generally in the form of a thin disk, is subjected to a very high pressure and concurrent torsional straining. Both of these processes are capable of producing metallic alloys with ultrafine grain sizes and with a reasonable degree of homogeneity. Furthermore, the samples produced in this way may exhibit exceptional mechanical properties including high strength at ambient temperature through the Hall-Petch relationship and a potential superplastic forming capability at elevated temperatures. This paper reviews these two procedures and gives examples of the properties of aluminum alloys after SPD processing.

Achieving Superplasticity and Superplastic Forming through Severe Plastic Deformation

2000 ◽  
Vol 634 ◽  
Author(s):  
Minoru Furukawa ◽  
Zenji Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Elevated Temperatures ◽  
Superplastic Forming ◽  
Ultrafine Grain ◽  
Strain Rates ◽  
Grain Sizes ◽  
Angular Pressing ◽  
Large Bulk ◽  
Processing Procedure

ABSTRACTThe application of severe plastic deformation to metals provides a convenient procedure for achieving nanometer and submicrometer microstructures. Several different processing methods are available but Equal-Channel Angular Pressing (ECAP) is especially attractive because it provides an opportunity for preparing relatively large bulk samples. This paper describes the use of ECAP in preparing materials with ultrafine grain sizes and the subsequent properties of these materials at elevated temperatures. It is demonstrated that, provided precipitates are present to retain these small grain sizes at the high temperatures where diffusion is reasonably rapid, it is possible to achieve remarkably high superplastic elongations in the as-pressed materials and there is a potential for making use of this processing procedure to develop a superplastic forming capability at very rapid strain rates.

Recent Developments in the Processing of Advanced Materials Using Severe Plastic Deformation

2021 ◽  
Vol 1016 ◽  
pp. 3-8
Author(s):  
Megumi Kawasaki ◽  
Roberto B. Figueiredo ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
High Hardness ◽  
Advanced Materials ◽  
Grain Sizes ◽  
Angular Pressing ◽  
Recent Developments ◽  
Bulk Nanocrystalline ◽  
Processing Techniques

The processing of bulk metals through the application of severe plastic deformation (SPD), using procedures such as equal-channel angular pressing (ECAP) and high-pressure torsion (HPT), is now well established for the fabrication of materials with exceptionally small grain sizes, usually in the submicrometer range and often having grain sizes at the nanometer level. These grain sizes cannot be achieved using thermo-mechanical processing or any conventional processing techniques. Recently, these procedures have been further developed to process alternative advanced materials. For example, by stacking separate disks within the HPT facility for the synthesis of bulk nanocrystalline metastable alloys where it is possible to achieve exceptionally high hardness, or by pressing powders or metallic particles in order to obtain new and novel nanocomposites exhibiting unusual properties.

Development of Complex Methods, Combining Thermal Treatment with Severe Plastic Deformation, for Processing of High-Strength Nanostructured Cu-1%Cr-0.7%Al Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 515-520 ◽  
Author(s):  
Igor V. Alexandrov ◽  
V.V. Latysh ◽  
Sun Ig Hong ◽  
S.N. Faizova ◽  
V.M. Polovnikov
Keyword(s):  
Plastic Deformation ◽  
Thermal Treatment ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
High Strength ◽  
Al Alloy ◽  
Thermal Treatments ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Complex Methods

The current work presents new results of investigation of properties and structure of nanocrystalline and submicrocrystalline Cu-1%Cr-0.7%Al alloy. Two severe plastic deformation (SPD) techniques were applied to refine the structure: high pressure torsion and equal-channel angular pressing (ECAP). The first technique was applied to conduct preliminary studies of the alloy different thermal treatments as before SPD as well as after it. A new technological thermomechanical technique for processing of bulk billets of Cu-1%Cr-0.7%Al alloy possessing an ultrafine grained structure was developed on the basis of the obtained results. This technique comprises a combination of ECAP and other deformational processes with the thermal treatment. High values of the tensile strength and yield stress - 700 MPa and 16% accordingly – have been obtained as a result of such treatment, whereas these values after conventional treatment consisted 450 MPa and 20% respectively.

Extending Creep and Superplasticity to Materials with Submicrometer Grain Sizes

2007 ◽  
Vol 345-346 ◽  
pp. 539-544
Author(s):  
Megumi Kawasaki ◽  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloys ◽  
Severe Plastic Deformation ◽  
Flow Behavior ◽  
Ultrafine Grain ◽  
Grain Sizes ◽  
Large Samples ◽  
Angular Pressing ◽  
Recent Advances ◽  
Ultrafine Grained

The mechanisms of creep and superplasticity occurring in conventional large-grained materials are now understood reasonably well. However, very recent advances in the processing of theoretically-dense metals with submicrometer grain sizes have provided the opportunity to extend the understanding of flow behavior to include materials where the grains are exceptionally small. Using processing through the application of severe plastic deformation, as in procedures such as equal-channel angular pressing, it is now feasible to fabricate relatively large samples having ultrafine grain sizes in the submicrometer or nanometer range. This paper examines these recent advances and gives examples of the flow behavior in ultrafine-grained aluminum alloys.

MULTI-SCALE FINITE ELEMENT SIMULATION OF SEVERE PLASTIC DEFORMATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1621-1626
Author(s):  
HYOUNG SEOP KIM
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Severe Plastic Deformation ◽  
Constitutive Model ◽  
Dislocation Cell ◽  
Ultrafine Grain ◽  
Angular Pressing ◽  
Element Simulation ◽  
Ultrafine Grain Size ◽  
Ultrafine Grained

The technique of severe plastic deformation (SPD) enables one to produce metals and alloys with an ultrafine grain size of about 100 nm and less. As the mechanical properties of such ultrafine grained materials are governed by the plastic deformation during the SPD process, the understanding of the stress and strain development in a workpiece is very important for optimizing the SPD process design and for microstructural control. The objectives of this work is to present a constitutive model based on the dislocation density and dislocation cell evolution for large plastic strains as applied to equal channel angular pressing (ECAP). This paper briefly introduces the constitutive model and presents the results obtained with this model for ECAP by the finite element method.

Role of Strain Gradient and Dynamic Transformation on the Formation of Nanocrystalline Structure Produced by Severe Plastic Deformation

2007 ◽  
Vol 539-543 ◽  
pp. 2787-2792 ◽  
Author(s):  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Jin Guo Li ◽  
Koichi Tsuchiya
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Strain Gradient ◽  
High Pressure Torsion ◽  
Large Strain ◽  
Nanocrystalline Structure ◽  
Angular Pressing ◽  
Dynamic Transformation ◽  
Fine Grained Structure

Formation of nanocrystalline structure by severe plastic deformation has studied extensively. Although ultra fine grained structure (grain size larger than 100 nm) had been obtained in many processes such as heavy cold rolling, equal channel angular pressing (ECAP) or accumulative roll bonding (ARB), the formation of nano grained structure (< 100 nm) is limited to processes such as ball milling, shot peening or drilling. In the present study, high pressure torsion (HPT) deformation and drilling were carried out to understand the conditions necessary to obtain nano grained structure in steels. The results of HPT experiments in pure Fe showed that HPT has superior ability of strengthening and grain refinement probably due to a strain gradient but the saturation of grain refinement occurs before reaching nano grained structure. Drilling experiments in high carbon martensitic steel revelaed that nano grained ferrite forms at the drilled hole surface only when the transformation from ferrite to austenite takes place during drilling. Considering various other processes by which nano grained ferrite was produced, it is proposed that heavy strains with large strain gradients together with dynamic transformation are necessary to reach nano grained ferrite structure.

scholarly journals Determination of microstructural changes by severely plastically deformed copper-aluminum alloy: Optical study

2014 ◽  
Vol 50 (1) ◽  
pp. 61-68 ◽  
Author(s):  
N. Romcevic ◽  
M. Gilic ◽  
I. Anzel ◽  
R. Rudolf ◽  
M. Mitric ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Structural Characteristics ◽  
Al Alloy ◽  
Local Structures ◽  
Angular Pressing ◽  
Aluminum Solid Solution ◽  
Oxide Particles ◽  
Copper Aluminum ◽  
Nanosized Oxide

Our work deals with the problem of producing a complex metal-ceramic composite using the processes of internal oxidation (IO) and severe plastic deformation. For this purpose, Cu-Al alloy with 0.4wt.% of Al was used. IO of sample serves in the first step of the processing as a means for attaining a fine dispersion of nanosized oxide particles in the metal matrix. Production technology continues with repeated application of severe plastic deformation (SPD) of the resulting metalmatrix composite to produce the bulk nanoscaled structural material. SPD was carried out with equal channel angular pressing (ECAP), which allowed that the material could be subjected to an intense plastic strain through simple shear. Microstructural characteristics of one phase and multiphase material was studied on internally oxidized Cu with 0.4wt.% of Al sample composed of one phase copper-aluminum solid solution in the core and fine dispersed oxide particles in the same matrix in the mantle region. In this manner AFM, X-ray diffraction and Raman spectroscopy were used. Local structures in plastically deformed samples reflect presence of Cu, CuO, Cu2O, Cu4O3 or Al2O3 structural characteristics, depending on type of sample.

THE PROPERTIES OF BULK ULTRAFINE-GRAINED METALS PROCESSED THROUGH THE APPLICATION OF SEVERE PLASTIC DEFORMATION

2012 ◽  
Vol 05 ◽  
pp. 299-306
Author(s):  
TERENCE G. LANGDON
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Elevated Temperatures ◽  
High Pressure Torsion ◽  
Superplastic Forming ◽  
High Strength ◽  
Basic Principles ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Processing Techniques

Processing through the application of severe plastic deformation (SPD) provides a very attractive tool for the production of bulk ultrafine-grained materials. These materials typically have grain sizes in the submicrometer or nanometer ranges and they exhibit high strength at ambient temperature and, if the ultrafine grains are reasonably stable at elevated temperatures, they have a potential for use in superplastic forming operations. Several procedures are now available for applying SPD to metal samples but the most promising are Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT). This paper examines the basic principles of ECAP and HPT and describes some of the properties that may be achieved using these processing techniques.

Aging Behaviour of Aluminium Alloys after Severe Plastic Deformation

2006 ◽  
Vol 519-521 ◽  
pp. 1485-1492 ◽  
Author(s):  
Z. Horita
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strength ◽  
Age Hardening ◽  
Precipitation Process ◽  
Al Alloy ◽  
Metallic Materials ◽  
Aging Behavior ◽  
Angular Pressing ◽  
Transmission Electron

The process of severe plastic deformation (SPD) makes it possible to reduce the grain size to the submicrometer or nanometer range in many metallic materials. When the SPD process is applied to age hardenable alloys, it may also be possible to control aging behavior. In this study, a technique of equal-channel angular pressing (ECAP) is used as an SPD process and aging behavior is examined on the three selected Al alloy systems such as Al-Ag, Al-Mg-Si and Al-Si-Ge. The microstructures are observed using transmission electron microscopy and the mechanical properties including hardness are measured. It is shown that the SPD process introduces unusual phenomena in the precipitation process and there should be a potential for enhancement of strength over the conventional age-hardening process or for improvement of ductility while keeping the high strength.

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