scholarly journals Achieving Superplasticity in Fine-Grained Al-Mg-Sc Alloys

2021 ◽  
Vol 1016 ◽  
pp. 11-17
Author(s):  
Pedro H.R. Pereira ◽  
Yi Huang ◽  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Superplastic Forming ◽  
Superplastic Flow ◽  
Alternative Procedure ◽  
Flow Mechanism ◽  
Friction Stir ◽  
Fine Grained ◽  
Angular Pressing

Superplasticity denotes the ability of a limited number of materials to achieve exceptionally high tensile elongations of at least 400%. Experiments show that the Al-Mg-Sc alloys provide excellent capabilities for achieving superplastic flow and also they can be formed easily in biaxial superplastic forming operations. It is important, therefore, to examine the superplastic flow mechanism when the alloy is prepared using different procedures. This report examines the superplastic characteristics of these alloys after preparation without subjecting to any severe plastic deformation (SPD), after processing using the two SPD procedures of equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) and after processing using the alternative procedure of friction stir processing (FSP). The results are compared using each technique and they are examined with reference to a theoretical model that was developed specifically for superplastic flow in conventional alloys.

Positron Annihilation Studies of Microstructure of Ultra Fine Grained Metals Prepared by Severe Plastic Deformation

2005 ◽  
Vol 482 ◽  
pp. 207-210 ◽  
Author(s):  
Jakub Čížek ◽  
Ivan Procházka ◽  
Bohumil Smola ◽  
Ivana Stulíková ◽  
Radomír Kužel ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Spatial Distribution ◽  
Severe Plastic Deformation ◽  
Positron Annihilation ◽  
Equal Channel Angular Pressing ◽  
High Pressure Torsion ◽  
Positron Annihilation Spectroscopy ◽  
Fine Grained ◽  
Angular Pressing

In the present work, positron annihilation spectroscopy (PAS) is employed for microstructure investigations of various ultra fine grained (UFG) metals (Cu, Ni, Fe) prepared by severe plastic deformation (SPD), namely high-pressure torsion (HPT) and equal channel angular pressing (ECAP). Generally, UFG metals prepared using both the techniques exhibit two kinds of defects introduced by SPD: dislocations and small microvoids. The size of the microvoids is determined from the PAS data. Significantly larger microvoids are found in HPT deformed Fe and Ni compared to HPT deformed Cu. The microstructure of UFG Cu prepared by HPT and ECAP is compared and the spatial distribution of defects in UFG Cu samples is characterized. In addition, the microstructure of a pure UFG Cu prepared by HPT and HPT deformed Cu+Al2O3 nanocomposite (GlidCop) is compared.

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.

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.

Recrystallization and Grain Growth in Ultra Fine Grained Materials Produced by High Pressure Torsion

2012 ◽  
Vol 715-716 ◽  
pp. 373-373
Author(s):  
Anahita Khorashadizadeh ◽  
Myrjam Winning ◽  
Stefan Zaefferer ◽  
Dierk Raabe
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Growth ◽  
High Pressure Torsion ◽  
Fine Grained ◽  
Fine Grained Material

Investigations of the microstructure of materials processed via severe plastic deformation methods such as high pressure torsion (HPT) and their recrystallization behaviour is of great interest as they are capable of producing ultra fine grained material (UFD) with good mechanical properties.

scholarly journals Dynamic High Pressure Torsion (DHPT)—A Novel Method for High Strain Rate Severe Plastic Deformation

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 493 ◽  
Author(s):  
Harishchandra Lanjewar ◽  
Leo Kestens ◽  
Patricia Verleysen
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
High Pressure Torsion ◽  
Pure Aluminum ◽  
High Deformation ◽  
Fine Grained

Metals with a fine-grained microstructure have exceptional mechanical properties. Severe plastic deformation (SPD) is one of the most successful ways to fabricate ultrafine-grained (UFG) and nanostructured (NC) materials. Most of the SPD techniques employ very low processing speeds. However, the lowest steady-state grain size which can be obtained by SPD is considered to be inversely proportional with the strain rate at which the severe deformation is imposed. In order to overcome this limitation, methods operating at higher rates have been envisaged and used to study the fragmentation process and the properties of the obtained materials. However, almost none of these methods, employ hydrostatic pressures which are needed to prevent the material from failing at high deformation strains. As such, their applicability is limited to materials with a high intrinsic ductility. Additionally, in some methods the microstructural changes are limited to the surface layers of the material. To circumvent these restrictions, a novel facility has been designed and developed which deforms the material at high strain rate under high hydrostatic pressures. Using the facility, commercially pure aluminum was processed and analysis of the deformed material was performed. The microstructure evolution in this material was compared with that observed in static high pressure torsion (HPT) processed material.

Analysis of the Fundamental Mechanisms and Efficiency of the Deformation Methods of Nanostructuring

2008 ◽  
Vol 584-586 ◽  
pp. 29-34 ◽  
Author(s):  
Radik R. Mulyukov ◽  
Ayrat A. Nazarov ◽  
Renat M. Imayev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
High Temperature ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Efficient Method ◽  
High Pressure Torsion ◽  
Angular Pressing

Deformation methods of nanostructuring (DMNs) of materials are proposed to classify into severe plastic deformation (SPD) and mild plastic deformation (MPD) methods according to fundamentally different low- and high-temperature grain refinement mechanisms they exploit. A general analysis of the fundamentals and nanostructuring efficiency of three most developed DMNs, high pressure torsion (HPT), equal-channel angular pressing (ECAP), and multiple isothermal forging (MIF) is done with a particular attention to ECAP and MIF. It is demonstrated that MIF is the most efficient method of DMNs allowing one to obtain the bulkiest nanostructured samples with enhanced mechanical properties.

Microstructure and Mechanical Properties of the SPD-Processed TiNi Alloys

2013 ◽  
Vol 738-739 ◽  
pp. 486-490 ◽  
Author(s):  
Dmitriy Gunderov ◽  
Alexandr Lukyanov ◽  
Egor Prokofiev ◽  
Anna Churakova ◽  
Vladimir Pushin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Cold Rolling ◽  
High Pressure Torsion ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
First Results ◽  
Equal Channel Angular Pressure

The article represents results of influence of different severe plastic deformation (SPD) techniques on TiNi alloys. It is demonstrated that strength and shape memory effect (SME) of TiNi can be significantly enhanced due to formation of ultrafine-grained (UFG) and nanocrystalline (NC) structures by SPD. Influence of equal channel angular pressing (ECAP), high pressure torsion (HPT), multi-step SPD deformations (ECAP plus cold rolling) on structure, mechanical and functional properties of TiNi alloys is considered. There are represented first results of influence of equal channel angular pressure-Conform (ECAP-C) on TiNi alloys, which is a perspective technology for industrial fabrication of UFG metals and alloys.

Bulk Ultrafine and Nanostructured Materials from Consolidation of Particles by Severe Plastic Deformation

2008 ◽  
Vol 579 ◽  
pp. 61-74 ◽  
Author(s):  
Kenong Xia
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Nanostructured Materials ◽  
High Pressure Torsion ◽  
Processing Parameters ◽  
Back Pressure ◽  
Angular Pressing ◽  
Important Processing

The progress in bulk ultrafine and nanostructured materials through consolidation of particles by severe plastic deformation (SPD) is reviewed. The focus is on the processes of high pressure torsion (HPT) and equal channel angular pressing (ECAP) with or without the application of a back pressure. Various materials consolidated are described in terms of their densities, microstructures and mechanical properties. The important processing parameters and their effects on the resulting materials are discussed. It is shown that SPD consolidation of particles is an effective way of producing bulk nanostructured materials although much work is needed to understand the consolidation behaviour and to design the optimum compositions and microstructures.

Microstructure of Ultra Fine Grained Mg and Mg-10 wt.% Gd Prepared by High-Pressure Torsion

Magnesium ◽  
2005 ◽  
pp. 202-207
Author(s):  
J. Cizek ◽  
I. Prochazka ◽  
I. Stulikova ◽  
B. Smola ◽  
R. Kuzel ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Fine Grained

GRAIN REFINEMENT AND MICROSTRUCTURE EVOLUTION IN ALUMINUM A2618 ALLOY BY HIGH-PRESSURE TORSION

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Intan Fadhlina Mohamed ◽  
Seungwon Lee ◽  
Kaveh Edalati ◽  
Zenji Horita ◽  
Shahrum Abdullah ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Grain Refinement ◽  
Room Temperature ◽  
Rotation Speed ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Saturation Level ◽  
Microstructural Refinement ◽  
Average Grain Size

This work presents a study related to the grain refinement of an aluminum A2618 alloy achieved by High-Pressure Torsion (HPT) known as a process of Severe Plastic Deformation (SPD). The HPT is conducted on disks of the alloy under an applied pressure of 6 GPa for 1 and 5 turns with a rotation speed of 1 rpm at room temperature. The HPT processing leads to microstructural refinement with an average grain size of ~250 nm at a saturation level after 5 turns. Gradual increases in hardness are observed from the beginning of straining up to a saturation level. This study thus suggests that hardening due to grain refinement is attained by the HPT processing of the A2618 alloy at room temperature.

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