Effect of Severe Plastic Deformation on the Structure and Properties of the Age-Hardenable Mg-Sm Alloys

2006 ◽  
Vol 503-504 ◽  
pp. 961-966 ◽  
Author(s):  
L.L. Rokhlin ◽  
Sergey V. Dobatkin ◽  
Tatiana V. Dobatkina ◽  
N.I. Nikitina ◽  
Mikhail V. Popov

In this work severe plastic deformation (SPD) was applied to magnesium base alloys of the Mg-Sm system (2.8-5.5 mass %Sm). These alloys are characterized by high strength at elevated temperatures and high strengthening effect during aging. SPD was performed by torsion under pressure of 4 GPa at 20 and 200°C to ε ∼ 6. SPD results in significant strengthening of the Mg-Sm alloys due to the formation of submicrocrystalline structure. In all cases SPD accelerates the solid solution decomposition upon subsequent aging. The highest strengthening can be obtained if the solution treated alloy is aged at 200°C after SPD at room temperature. The state of high strength can be also reached if the following sequence of the operations is used: solution treatment + aging at 200 °C up to maximum hardness + SPD at 20°C + aging at 200°C accompanied by Sm –rich phase precipitation in the submicrocrystalline matrix.

2006 ◽  
Vol 519-521 ◽  
pp. 45-54 ◽  
Author(s):  
Terence G. Langdon

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.


2012 ◽  
Vol 05 ◽  
pp. 299-306
Author(s):  
TERENCE G. LANGDON

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.


2017 ◽  
Vol 892 ◽  
pp. 64-69 ◽  
Author(s):  
Igor Altenberger ◽  
Hans Achim Kuhn ◽  
Mozhgan Gholami-Kermanshahi ◽  
Mansour Mhaede ◽  
Manfred Wollmann ◽  
...  

Ultrafine-grained (UFG) pure copper has been in the focus of materials scientists over the last two decades, however ultrafine-grained high-strength copper alloys have scarcely been processed or characterized so far industrially.In this contribution, UFG copper alloys, especially Cu-Ni-Si alloys, being well known as ideal materials for electromechanical connectors, springs and leadframes, are presented. Precipitation hardened Cu-Ni-Si alloys are a well established and technologically important class of materials for a wide range of applications where high strength and good conductivity are required. Yield strength and fatigue properties of metallic alloys can be significantly enhanced by severe plastic deformation methods. In contrast to other strengthening methods such as solid solution hardening, severe plastic deformation leads to a weaker decrease of electrical conductivity and is therefore a means of enhancing strength while maintaining acceptable conductivity for current bearing parts and components. Characterization of these materials after severe plastic deformation by swaging, wire drawing and subsequent aging was carried out using conductivity-, hardness-and tensile tests as well as highly-resolved microstructural characterization methods.The results reveal that UFG low alloyed copper alloys exhibit impressive combinations of properties such as strength, conductivity, high ductility as well as acceptable thermal stability at low and medium temperatures. By a subsequent aging treatment the severely plastically deformed microstructure of Cu-Ni-Si alloys can be further enhanced and thermal stability can profit from grain-boundary pinning by precipitated nanoscale nickel silicides.


2005 ◽  
Vol 488-489 ◽  
pp. 629-632 ◽  
Author(s):  
Qu Dong Wang ◽  
Yongjun Chen ◽  
Jianguo Peng ◽  
Man Ping Liu ◽  
Wen Jiang Ding ◽  
...  

Microstructure and mechanical properties of AM50+xTi (x=0,0.01,0.1wt%) magnesium alloys extruded from as-cast and solution treated conditions have been studied. Results show that Ti element obviously refines the microstructure of AM50 magnesium alloy and Mg17Al12 phase. Only 0.01 wt% Ti addition can make the Mg17Al12 phase turn into particles and small rod-like shape. Ti addition improves tensile strength at room temperature, and obviously improves elongation at elevated temperatures up to 200°C. The AM50+xTi alloys extruded from as-cast have better tensile strength at room temperature and better elongation at 100°C, 150°C and 200°C than that of AM50+xTi alloys extruded from solution treatment; The plasticity of AM50 magnesium alloys increases with Ti content increasing and temperature increasing for the tensile fractograph.


2010 ◽  
Vol 667-669 ◽  
pp. 45-49
Author(s):  
Farid Z. Utyashev

Nanostructured (NS) metallic materials can exhibit high strength at room temperature and superplastic properties at elevated temperatures. This enables to enhance their technological and structural properties, when producing various parts from them. For producing NS materials by severe plastic deformation (SPD), the development of effective SPD techniques for practical use is an urgent task. It is shown that solution of such a task should take into account strain compatibility on the macro-, meso- and micro-levels. Not only shear but also rotational deformation mode should be considered. Properties of NS materials and possibilities of their structural applications are considered from this point of view.


2014 ◽  
Vol 794-796 ◽  
pp. 851-856
Author(s):  
Tadashiege Nagae ◽  
Nobuhiro Tsuji ◽  
Daisuke Terada

Accumulative roll-bonding (ARB) process is one of the severe plastic deformation processes for fabricating ultrafine grained materials that exhibit high strength. In aluminum alloys, aging heat treatment has been an important process for hardening materials. In order to achieve good mechanical properties through the combination of grain refinement hardening and precipitation hardening, an Al-4.2wt%Ag binary alloy was used in the present study. After a solution treatment at 550°C for 1.5hr, the alloy was severely deformed by the ARB process at room temperature (RT) up to 6 cycles (equivalent strain of 4.8). The specimens ARB-processed by various cycles (various strains) were subsequently aged at 100, 150, 200, 250°C, and RT. The hardness of the solution treated (ST) specimen increased by aging. On the other hand, hardness of the ARB processed specimen decreased after aging at high temperatures such as 250°C. This was probably due to coarsening of precipitates or/and matrix grains. The specimen aged at lower temperature showed higher hardness. The maximum harnesses achieved by aging for the ST specimen, the specimens ARB processed by 2 cycles, 4 cycles and 6 cycles were 55HV, 71HV, 69HV and 65HV, respectively. By tensile tests it was shown that the strength increased by the ARB process though the elongation decreased significantly. However, it was found that the tensile elongation of the ARB processed specimens was improved by aging without sacrificing the strength. The results suggest that the Al-Ag alloy having large elongation as well as high strength can be realized by the combination of the ARB process for grain refinement and the subsequent aging for precipitation hardening.


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3467
Author(s):  
Anna Nocivin ◽  
Doina Raducanu ◽  
Bogdan Vasile ◽  
Corneliu Trisca-Rusu ◽  
Elisabeta Mirela Cojocaru ◽  
...  

The present paper analyzed the microstructural characteristics and the mechanical properties of a Ti–Nb–Zr–Fe–O alloy of β-Ti type obtained by combining severe plastic deformation (SPD), for which the total reduction was of etot = 90%, with two variants of super-transus solution treatment (ST). The objective was to obtain a low Young’s modulus with sufficient high strength in purpose to use the alloy as a biomaterial for orthopedic implants. The microstructure analysis was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) investigations. The analyzed mechanical properties reveal promising values for yield strength (YS) and ultimate tensile strength (UTS) of about 770 and 1100 MPa, respectively, with a low value of Young’s modulus of about 48–49 GPa. The conclusion is that satisfactory mechanical properties for this type of alloy can be obtained if considering a proper combination of SPD + ST parameters and a suitable content of β-stabilizing alloying elements, especially the Zr/Nb ratio.


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