Critical review of mechanism of superplastic deformation in fine grained metallic materials

2000 ◽  
Vol 16 (11-12) ◽  
pp. 1287-1294 ◽  
Author(s):  
R.I. Todd
Keyword(s):  
Critical Review ◽  
Superplastic Deformation ◽  
Metallic Materials ◽  
Fine Grained

A Comparative Study on Superplasticity of Mg-Zn-Y-Zr Processed by ECAE and Hot Rolling

2007 ◽  
Vol 551-552 ◽  
pp. 203-208 ◽  
Author(s):  
Wei Neng Tang ◽  
Hong Yan ◽  
Rong Shi Chen ◽  
En Hou Han
Keyword(s):  
Hot Rolling ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Sensitivity Coefficient ◽  
Grain Boundary Sliding ◽  
Diffusional Creep ◽  
Dislocation Creep ◽  
Fine Grained ◽  
Microstructure Observation ◽  
Elongation To Failure

Superplastic deformation (SPD) behaviors of two fine-grained materials produced by ECAE and hot rolling methods have been contrastively studied in this paper. It is found that the optimum superplastic condition in as-ECAEed material was at 350°C and 1.7×10-3s-1 with elongation to failure about 800%; while in as-rolled material, the largest elongation to failure about 1000% was obtained at 480°C and 5.02×10-4s-1. Microstructure observation showed that grain evolution and cavitation behavior were different in these two materials during superplastic deformation. The controlled mechanisms for superplasticity, i.e. grain boundary sliding (GBS), dislocation creep and diffusional creep, at different deformation conditions were discussed in terms of strain rate sensitivity coefficient, stress exponent and activity energy.

scholarly journals Superplastic deformation of fine-grained AE42 and LAE442 magnesium alloys

2018 ◽  
Vol 8 (4) ◽  
pp. 538-542
Author(s):  
P. Minárik ◽  
T. Vávra ◽  
J. Stráský ◽  
B. Hadzima ◽  
R. Král
Keyword(s):  
Magnesium Alloys ◽  
Superplastic Deformation ◽  
Fine Grained

Shear Pressing for Grain Refinement of Al-Mg-Li Sheet

2007 ◽  
Vol 546-549 ◽  
pp. 885-888
Author(s):  
Yu Xuan Du ◽  
Xin Ming Zhang ◽  
Ling Ying Ye ◽  
Zhi Hui Luo
Keyword(s):  
Shear Deformation ◽  
Grain Refinement ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Grain Refining ◽  
Metallic Materials ◽  
Inclined Plane ◽  
Fine Grained ◽  
Electron Backscatter ◽  
Backscatter Diffraction

A novel shear-deformation technique, named ‘shear pressing’ (SP), was developed for fabrication of plate-shaped fine grained metallic materials. The principle of SP is that a material is subjected to shear deformation by utilizing pressing with inclined plane dies. A micrometer order grain structure was obtained in an Al-Mg-Li alloy at strain of ε = -2.3 by utilizing this technique. The grain refinement sequences during pressing were examined by electron backscatter diffraction. The enhancement of grain refinement to the Al-Mg-Li alloy was compared with plane strain compression (PSC) at similar strains. The effect of the shear strain on the accelerated grain refining during compressing has been discussed.

scholarly journals Superplastic deformation behavior of ultra-fine-grained Ti-1V-4Al-3Mo alloy: constitutive modeling and processing map

2019 ◽  
Vol 6 (9) ◽  
pp. 096584 ◽  
Author(s):  
A O Mosleh ◽  
A V Mikhaylovskaya ◽  
A D Kotov ◽  
M Sitkina ◽  
P Mestre-Rinn ◽  
...  
Keyword(s):  
Constitutive Modeling ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
Processing Map ◽  
Fine Grained

Types of Negation

2020 ◽  
pp. 57-74
Author(s):  
Karen De Clercq
Keyword(s):  
Critical Review ◽  
Careful Analysis ◽  
The Other ◽  
Fine Grained ◽  
Other Hand ◽  
The One

This chapter discusses the well-known dichotomies between sentence negation and constituent negation on the one hand and external negation and internal negation on the other hand. It explains how the notions differ and where they show overlap. Crucial in this discussion is the presentation and critical review of some of the most relevant tests for negation as discussed by Klima (1964). The discussion leads to the observation that both sentence negation and constituent negation are umbrella terms for multiple scopal types of negation. The chapter further shows how a careful analysis of negative morphology can be insightful in putting up a more fine-grained classification that does better justice to the reality of negative markers than captured by the well-known dichotomies.

Effect of Silver on Superplastic Deformation in YBa2Cu3O7–x/Ag Composites

2002 ◽  
Vol 17 (5) ◽  
pp. 1172-1177
Author(s):  
Jondo Yun ◽  
Ye T. Chou ◽  
Martin P. Harmer
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Superplastic Deformation ◽  
Close Agreement ◽  
Silver Content ◽  
Strain Rates ◽  
Compression Tests ◽  
Fine Grained ◽  
Soft Inclusion ◽  
Activation Energy Of Deformation

Superplastic deformation was studied in fine-grained (0.7–1.1 μm) YBa2Cu3O7–x/Ag composites containing 2.5–25 vol% Ag. The compression tests were conducted in the temperature range of 750–875 °C and at strain rates of 10−5 to 10−3/s. For the YBa2Cu3O7−x/25%Ag composites with grain size of 0.7–1.1 μm, deformed at 800–850 °C and 10−5 to 10−3/s, the stress exponent, grain size exponent, and the activation energy of deformation were 2.0 ± 0.1, 2.5 ± 0.7, and 760 ± 100 kJ/mol, respectively. These values were the same as those of the pure YBa2Cu3O7−x, indicating that the deformation of the composite was controlled by that of the rigid YBa2Cu3O7−x phase. However, the strain rate was increased by the addition of silver as explained by the soft inclusion model of Chen. The dependence of the flow stress on the silver content was in close agreement with the prediction of the model.

Grain Refinement of Copper Alloys by Equal Channel Angular Pressing

2004 ◽  
Vol 449-452 ◽  
pp. 177-180 ◽  
Author(s):  
Cha Yong Lim ◽  
Jae Hyuck Jung ◽  
Seung Zeon Han
Keyword(s):  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Copper Alloys ◽  
Metallic Materials ◽  
Fine Grained ◽  
Angular Pressing ◽  
Fine Grain ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Average Grain Size

The equal channel angular pressing (ECAP) is one of the methods to refine the grain size of metallic materials. This study investigates the effect of ECAP process on the formation of the fine grain size in oxygen free Cu and Cu alloys. The average grain size has been refined from 150 µm before ECAP to 300 nm. Microstructure was analyzed by transmission electron micrography (TEM). The diffraction pattern of the selected area confirmed the formation of ultrafine-grained structure with high angle grain boundaries after 8 cycles of ECAP. Mechanical properties such as microhardness and tensile properties of the ultra-fine grained copper materials have been investigated.

Microstructural Evolution of a Fine-Grained Mg-Y-Nd Alloy during Superplastic Deformation

2016 ◽  
Vol 849 ◽  
pp. 162-167
Author(s):  
Geng Hua Cao ◽  
Da Tong Zhang
Keyword(s):  
Electron Microscopy ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Second Phase ◽  
Friction Stir ◽  
Fine Grained ◽  
Average Grain Size ◽  
Temperature Ranges ◽  
Increasing Temperature

Cast Mg-4.27Y-2.94Nd-0.51Zr (wt.%) alloy was subjected to submerged friction stir processing (SFSP) with at a rotation rate of 600 rpm and a traveling speed of 60 mm min-1. Superplastic behavior of specimens with an average grain size of ~1.3 μm were investigated in the temperature ranges of 683-758 K and the strain rate ranges from 1×10-1 to 4×10-4 s-1. Microstructure characteristics were investigated by optical microscopy, scanning electron microscopy and transmission electron microscopy. The results show that the maximum elongation of 967% was obtained at 733 K and 3×10-3 s-1, the optimal HSRS of 900% achieved at 758 K and 2×10-2 s-1. Grains and second phase particles grew coarser with the increasing temperature or decreasing strain rate. Remarkable grain growth is the main reason that elongations are all significantly decreased when the strain rate decrease from 3×10-3 s-1 to 4×10-4 s-1. Grain boundary sliding is the main mechanism during superplastic deformation.

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