Influence of stacking fault energy on microstructural development in equal-channel angular pressing

1999 ◽  
Vol 14 (10) ◽  
pp. 4044-4050 ◽  
Author(s):  
Shogo Komura ◽  
Zenji Horita ◽  
Minoru Nemoto ◽  
Terence G. Langdon
Keyword(s):  
Grain Size ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Ultrafine Grain ◽  
Microstructural Development ◽  
Angular Pressing ◽  
Ultrafine Grain Size ◽  
Slow Evolution ◽  
Static Annealing ◽  
Pure Cu

Equal-channel angular (ECA) pressing is a procedure having the capability of introducing an ultrafine grain size into a material. Experiments were conducted to examine the effect of the low stacking fault energy in pure Cu on microstructural development during ECA pressing at room temperature. The results show that the low 0stacking fault energy and the consequent low rate of recovery lead to a very slow evolution of the microstructure during pressing. Ultimately, a stable grain size of −0.27 μm was established in pure Cu but the microstructure was not fully homogeneous even after pressing to a total strain of ∼10. It is shown by static annealing that the as-pressed grains are stable up to ∼400 K, but at higher temperatures there is grain growth. These results lead to the conclusion that a low stacking fault energy is especially favorable for the introduction of an exceptionally small grain size using the ECA pressing procedure.

scholarly journals Correlation of Grain Size, Stacking Fault Energy, and Texture in Cu-Al Alloys Deformed under Simulated Rolling Conditions

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Ehab A. El-Danaf ◽  
Mahmoud S. Soliman ◽  
Ayman A. Al-Mutlaq
Keyword(s):  
Grain Size ◽  
Strain Hardening ◽  
Mechanical Twinning ◽  
Al Alloys ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Wide Range ◽  
Orientation Density ◽  
Pure Cu ◽  
Strain Hardening Rate

The effect of grain size and stacking fault energy (SFE) on the strain hardening rate behavior under plane strain compression (PSC) is investigated for pure Cu and binary Cu-Al alloys containing 1, 2, 4.7, and 7 wt. % Al. The alloys studied have a wide range of SFE from a low SFE of 4.5 mJm−2for Cu-7Al to a medium SFE of 78 mJm−2for pure Cu. A series of PSC tests have been conducted on these alloys for three average grain sizes of ~15, 70, and 250 μm. Strain hardening rate curves were obtained and a criterion relating twinning stress to grain size is established. It is concluded that the stress required for twinning initiation decreases with increasing grain size. Low values of SFE have an indirect influence on twinning stress by increasing the strain hardening rate which is reflected in building up the critical dislocation density needed to initiate mechanical twinning. A study on the effect of grain size on the intensity of the brass texture component for the low SFE alloys has revealed the reduction of the orientation density of that component with increasing grain size.

Grain Refinement of High-Purity FCC Metals Using Equal-Channel Angular Pressing

2007 ◽  
Vol 558-559 ◽  
pp. 1273-1278 ◽  
Author(s):  
Z. Horita ◽  
Kaoru Kishikawa ◽  
Keiichi Kimura ◽  
Kohei Tatsumi ◽  
Terence G. Langdon
Keyword(s):  
Equal Channel Angular Pressing ◽  
High Purity ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Grain Refining ◽  
Fcc Metals ◽  
Angular Pressing ◽  
The Difference ◽  
Pure Cu ◽  
Very High

Equal-channel angular pressing (ECAP) is a valuable technique for refining grain sizes to the submicrometer or the nanometer range. This study explores the reason for the difference in the grain refining behavior between pure Al and pure Cu. First, very high purity levels were adopted in order to minimize any effects of impurities: 99.999% for Al and 99.99999% for Cu. Second, high purity (99.999%) Au was also used in order to examine the effect of stacking fault energy. All three pure metals were subjected to ECAP and microstructural observations and hardness measurements were undertaken with respect to the number of ECAP passes. It is concluded that the stacking fault energy plays an important role and accounts for the difference in the grain refining behavior in the ECAP process.

The Effect of Process Route on the Mechanical Properties and Microstructure Aluminum Al-Si-Cu-Mg-Mn Alloys

2020 ◽  
Vol 402 ◽  
pp. 67-72
Author(s):  
Rahmawaty ◽  
Surya Dharma ◽  
Abdul Razak ◽  
Sarjianto ◽  
Nisfan Bahri ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
Solution Treatment ◽  
Hardness Test ◽  
Optical Microscope ◽  
Ultrafine Grain ◽  
Angular Pressing ◽  
Process Route ◽  
Ultrafine Grain Size

Equal-channel angular pressing (ECAP) is an effective fabrication process to modify ultrafine grain size. It is believed that the smaller grain size could improve the mechanical properties. In the present work, the solution treatment applied to Al-Si-Cu-Mg-Mn alloy. Furthermore, two models of ECAP have been done through one-to-three pass at room temperature. The microstructures were observed by optical microscope (OM) and scanning electron microscope (SEM). The micro-hardness of longitudinal plane was analyzed by vickers hardness test. The strength of ECAP materials at room temperature was obtained by using tensile test. The results show that the ECAP process has improved mechanical properties of alloys, which were the hardness and ultimate tensile strength tend to increase since single pass stage.

Study of Semisolid and ECAP Processes on Al-Fe-Si Alloy - Microstructure and Kinetic Grain Growth

2011 ◽  
Vol 312-315 ◽  
pp. 166-171 ◽  
Author(s):  
D. Azimi-Yancheshmeh ◽  
M. Aghaie-Khafri
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Optical Microscopy ◽  
Grain Growth ◽  
Ultrafine Grain ◽  
Angular Pressing ◽  
Ultrafine Grain Size ◽  
Heat Treated ◽  
Alloy Microstructure

ECAP (Equal Channel Angular Pressing) is one of the useful methods of Severe Plastic Deformation (SPD) to reach ultrafine grain size. ECAP was carried out on Al-Fe-Si alloy. All grains stretched along the ECAP direction. Samples were ECAPed for one pass into an ECAP mold with two equal channels (1 cm × 1 cm) with 90o between them. After ECAP, specimens were heat treated (semisolided) for different times and temperatures for achieving globular grains. Optical microscopy has been used to evaluate the microstructure. By ECAP and semisolid processes, the structure becomes fine and globular. The kinetic grain growth has been studied for this alloy by the calculation of the D = Ktn equation and log(D)-log(t) curves.

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.

Grain size effect on deformation twin thickness in a nanocrystalline metal with low stacking-fault energy

2019 ◽  
Vol 34 (13) ◽  
pp. 2398-2405
Author(s):  
Yusheng Li ◽  
Liangjuan Dai ◽  
Yang Cao ◽  
Yonghao Zhao ◽  
Yuntian Zhu
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Deformation Twin ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Grain Size Effect ◽  
Nanocrystalline Metal ◽  
Image Position ◽  
Twin Thickness

Abstract

Influence of Stacking Fault Energy on the Microstructures and Grain Refinement in the Cu-Al Alloys during Equal-Channel Angular Pressing

2010 ◽  
Vol 667-669 ◽  
pp. 379-384 ◽  
Author(s):  
X.H. An ◽  
Shi Ding Wu ◽  
Z.F. Zhang
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Al Alloys ◽  
Stacking Fault ◽  
High Recovery ◽  
Angular Pressing ◽  
High Recovery Rate ◽  
Refinement Mechanism ◽  
Stacking Fault Energies

The microstructural evolution and grain refinement of Cu-Al alloys with different stacking fault energies (SFEs) processed by equal-channel angular pressing (ECAP) were investigated. The grain refinement mechanism was gradually transformed from dislocation subdivision to twin fragmentation with tailoring the SFE of Cu-Al alloys. Concurrent with the transition of grain refinement mechanism, the grain size can be refined into from ultrafine region (1 m~100 nm) to the nanoscale (<100 nm) and then it is found that the minimum equilibrium grain size decreases in a roughly linear way with lowering the SFE. Moreover, in combination with the previous results, it is proposed that the formation of a uniform ultrafine microstructure can be formed more readily in the materials with high SFE due to their high recovery rate of dislocations and in the materials with low SFE due to the easy formation of a homogeneously-twinned microstructure.

The Effects of Free Space in Mould Cavity on Sandglass Extrusion

2005 ◽  
Vol 475-479 ◽  
pp. 2999-3002
Author(s):  
W.L. Lu ◽  
Y. Wang ◽  
Jin Tao Hai
Keyword(s):  
Grain Size ◽  
Free Space ◽  
Large Strain ◽  
Experimental Results ◽  
Experimental Result ◽  
Ultrafine Grain ◽  
Theory Analysis ◽  
Ultrafine Grain Size ◽  
Mould Cavity

Sandglass extrusion is an ultrafine grain size method. Due to the repetitive and multiple extrusions, large strain will be accumulated and ultafine grain size can be obtained. There are some factors that can affect the experimental result of sandglass extrusion. Among these factors, free space in mould cavity is very important, which can affect the forming of the fold during the extrusion. In this paper, the effects of free space in mould cavity on sandglass extrusion have been discussed and theory analysis and experimental results have been reported.

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