Evolution of the Plastic Deformation Mechanisms in a Compressed Mg-10Gd-2Y-0.5Zr Alloy

2012 ◽  
Vol 510 ◽  
pp. 628-633
Author(s):  
Qing Yu Hou ◽  
Jing Tao Wang ◽  
Zhen Yi Huang
Keyword(s):  
Plastic Deformation ◽  
Dynamic Recrystallization ◽  
Basal Slip ◽  
Shear Bands ◽  
Testing Temperature ◽  
Mechanical Twinning ◽  
Deformation Mechanisms ◽  
Strain Rates ◽  
Local Zone ◽  
Local Shear

This paper investigates the evolution of the deformation mechanisms in a homogenized Mg-10Gd-2Y-0.5Zr alloy ingot compressed at 300-500 °C and 0.1-20 s-1. It can be found that the basal slip and mechanical twinning are the major deformation mechanisms in the alloy compressed at 300 and 0.1-20 s-1. Increasing the testing temperature to 350 °C, basal slip, non-basal slip and mechanical twinning control the plastic deformation of the alloy compressed at 0.1-20 s-1. When the testing temperatures increase further to 400-500 °C, the mechanical twinning is replaced gradually by the local shear bands which are formed by dynamic recrystallization (DRX) grains (referred as transformation bands). The transformation bands have the trend to form the typical DRX microstructure with increasing the temperatures (might be caused by increasing testing temperatures or strain rates). Besides, the transformation bands can also be found in the sample compressed at 350 °C and 20 s-1when the temperature in the deformation alloy is high enough to activate non-basal slip and form DRX grains at local zone.

Deformation Behavior of ZK60 Magnesium Alloy at Elevated Temperature

2014 ◽  
Vol 788 ◽  
pp. 93-97 ◽  
Author(s):  
Chun Yan Wang ◽  
Hai Qun Qi ◽  
Kun Wu ◽  
Ming Yi Zheng
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Squeeze Casting ◽  
Testing Temperature ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Temperature Range ◽  
Zk60 Magnesium Alloy

The high temperature compressive tests of squeeze casting ZK60 magnesium alloy in the testing temperature range of 523-723K and strain rate range of 0.001-10s-1 were performed on Gleeble-1500D thermal simulator testing machine. Optical microscopy was performed to elaborate on the dynamic recrystallization (DRX) grain growth. TEM observation indicated that the mechanical twinning, dislocation slip, and dynamic recrystallization are the materials typical deformation features. Variations of flow behavior with deformation temperature as well as strain rate were analyzed. Analysis of the flowing deformation behavior and microstructure observations indicated that the flow localization was observed at lower testing temperature and higher strain rates. Dynamic recrystallization occurred at higher testing temperature and moderate strain rates, which improved the ductility of the material. The results indicated that at the testing temperatures lower than 573K and strain rates higher than 1s-1, the material exhibited flow instability manifesting as bands of flow localizations. These temperatures and strain rates should be avoided in processing the material. Dynamic recrystallization occurs in the temperature range 573-723K and the strain rate range 0.001-0.1s-1. The number of dynamic recrystallization grains is less at lower temperature and higher strain rate than higher temperature and lower strain rate. The dynamic recrystallization is inadequate at 573-623K while the dynamic recrystallization grain growth has been observed in the temperature range of 673-723K. Therefore it may be considered that the optimum processing parameters for hot working of squeeze casting ZK60 magnesium alloy are 648K and 0.001-0.01s-1, at which fine dynamic recrystallization microstructure can be obtained.

Compressive Deformation of ZK60 Magnesium Alloy at Elevated Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 631-634 ◽  
Author(s):  
Chun Yan Wang ◽  
Kun Wu ◽  
Ming Yi Zheng
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Flow Behavior ◽  
Testing Machine ◽  
Mechanical Twinning ◽  
Dislocation Slip ◽  
Strain Rates ◽  
Lower Temperature ◽  
Zk60 Magnesium Alloy

The high temperature compressive tests of squeeze casting ZK60 magnesium alloy with temperatures of 573-723K and strain rate in the range of 0.001-1s-1 were performed on Gleeble-1500D thermal simulator testing machine. Optical microscopy was performed to elaborate on the dynamic recrystallization (DRX) grain growth. TEM findings indicate that mechanical twinning, dislocation slip, and dynamic recrystallization are the materials typical deformation features. Variations of flow behavior with deformation temperature as well as strain rate were analyzed. Analysis of the flow behavior and microstructure observations indicated that flow localization was observed at lower temperature and higher strain rates, which should be avoided during mechanical processing. Dynamic recrystallization occurred at higher temperature and moderate strain rates, which improved the ductility of the material. The optimum hot working conditions for ZK60 alloy were suggested.

A Preliminary Analysis on Compression Twins in Magnesium

2007 ◽  
Vol 546-549 ◽  
pp. 297-300 ◽  
Author(s):  
Ping Yang ◽  
Li Meng ◽  
Q.G. Xie ◽  
F.E. Cui
Keyword(s):  
Factor Analysis ◽  
Low Temperature ◽  
Preliminary Analysis ◽  
Basal Slip ◽  
Shear Bands ◽  
Morphological Difference ◽  
Deformation Mechanisms ◽  
Orientation Relationships ◽  
Schmid Factor ◽  
Ebsd Technique

Basal slip and tension twinning are dominant deformation mechanisms of polycrystalline magnesium at low temperature. However, fracture originates mainly from compression twins or shear bands developed from compression twins. This work compared firstly the morphological difference of two types of twins. Then, the dependence of different deformation mechanisms on initial orientations is computed by Schmid factor analysis and compared with measured matrix orientations of twins. Finally, orientation relationships of compression twins with matrices are determined using EBSD technique and compared with theoretical value.

Hot Workability of Ultrafine-Grained Aluminum Alloy Produced by Severe Plastic Deformation of Al6063 Powder and Consolidation

2010 ◽  
Vol 667-669 ◽  
pp. 979-984 ◽  
Author(s):  
Hamed Asgharzadeh ◽  
Abdolreza Simchi ◽  
Hyoung Seop Kim
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Grain Structure ◽  
Al Alloy ◽  
Strain Rates ◽  
Hot Workability ◽  
Ultrafine Grained

Al6063 powder was subjected to severe plastic deformation via high-energy mechanical milling to prepare ultrafine-grained (UFG) aluminium alloy. Uniaxial compression test at various temperatures between 300 and 450 °C and strain rates between 0.01 and 1 s-1 was carried out to evaluate hot workability of the material. Microstructural studies were performed by EBSD and TEM. The average activation energy and strain rate sensitivity of the hot deformation process were determined to be 280 kJ mol-1 and 0.05, respectively. The deformation temperature and applied strain rate significantly affected the grain structure of UFG Al alloy. A finer grain structure was obtained at lower temperatures and higher strain rates. The formation of highly misoriented and equiaxed grains also revealed that dynamic recrystallization occurred upon hot deformation. Furthermore, elongated grains with high dislocation density were observed that disclosed partial dynamic recrystallization of the aluminum matrix.

Simulation of plastic deformation in a two-dimensional atomic glass by molecular dynamics IV

1989 ◽  
Vol 329 (1608) ◽  
pp. 613-640 ◽  
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Shear Strain ◽  
Applied Stress ◽  
Glassy State ◽  
Shear Bands ◽  
Atomic Clusters ◽  
Two Dimensional ◽  
Principal Mechanism ◽  
Local Shear

Plastic deformation in a structurally well-relaxed two-dimensional atomic glass was simulated by a computer molecular dynamics approach. The simulation, which was carried through yielding and to substantial plastic strains, demonstrated that the principal mechanism of plastic strain production is by local partly dilatant shear transformations nucleated preferentially in the boundaries of liquid-like material separating the small quasi-ordered domains that form when the glass is well relaxed. Under imposed forward shear-strain increments, local shear transformations in atomic clusters were found to be mostly in the same direction as the applied stress. There were, however, substantial levels of shear transformations in other random directions, including many opposed to the applied stress. In all instances, however, nucleaton of shear transformations reduced the Gibbs free energy monotonically, which is governed largely by the locked-in excess enthalpies of the glassy state. At shear strains above 15%, localization of shear into bands was observed to begin. This steadily intensified and formed well-defined sharp shear bands into which all the shear strain became concentrated by the end of the simulation at a strain of 27%. A strong correlation was found between the tendency for shear localization and retained shear-induced dilatation.

Deformation Mechanisms of Twinning-Induced Plasticity Steel Under Shock-Load: Investigated by Synchrotron X-Ray Diffraction

2019 ◽  
Vol 3 (3) ◽  
pp. 15
Author(s):  
Kun Yan ◽  
Mark Callaghan ◽  
Klaus-Dieter Liss
Keyword(s):  
High Strength ◽  
Orientation Distribution ◽  
High Energy ◽  
Mechanical Twinning ◽  
Deformation Mechanisms ◽  
Strain Rates ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compression Direction ◽  
Twip Steels

As an ideal candidate material for automobiles, twinning-induced plasticity (TWIP) steels possess excellent formability, high strength and high energy absorption ability during collision. This is attributed to its deformation mechanism of mechanical twinning, resulting in a high work hardening rate. In the current study, deformation mechanisms of low-stacking fault energy TWIP steel, under different strain rates between 0.01/s to 1581/s, were investigated by high-energy X-ray diffraction. After compression, grains with {110}||compression direction became favourable. Higher intensity was observed near brass and A components in the selected orientation distribution function (ODF) section (φ2 = 45°) for all the compressed specimens. The activity of twinning was found to be the highest in the specimens that had been compressed with medium–high strain rates (e.g., 100/s and 10/s), while the texture component related to slip had stronger intensity in the specimen deformed with a quasi-static strain rate (0.01/s).

An investigation of ductility and microstructural evolution in an Al−3% Mg alloy with submicron grain size

1993 ◽  
Vol 8 (11) ◽  
pp. 2810-2818 ◽  
Author(s):  
Jingtao Wang ◽  
Zenji Horita ◽  
Minoru Furukawa ◽  
Minoru Nemoto ◽  
Nikolai K. Tsenev ◽  
...  
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Grain Size ◽  
Low Temperature ◽  
Dynamic Recrystallization ◽  
Microstructural Evolution ◽  
Power Law ◽  
Solid Solution Alloy ◽  
Strain Rates ◽  
Nonequilibrium Grain Boundaries

A submicrometer-grained (SMG) Al−3% Mg solid solution alloy, with an initial grain size of ∼0.2 μm, was produced by intense plastic straining. Experiments show that tensile specimens of the SMG alloy exhibit high elongations to failure at low testing strain rates at the relatively low temperature of 403 K. The stress exponent is high (∼7–8) and calculations show deformation is within the region of power-law breakdown. The initial microstructure of the alloy consists of diffuse boundaries between highly deformed grains. At strain rates of ∼10−4 s−1 and lower, plastic deformation leads to dynamic recrystallization and the formation of highly nonequilibrium grain boundaries that gradually evolve into a more equilibrated configuration.

Evaluation of Critical Resolved Shear Stresses for Various Plastic Deformation Mechanisms To Understand Mechanical Properties of Magnesium-Yttrium Alloys

2015 ◽  
Vol 1741 ◽  
Author(s):  
T. Mineta ◽  
S. Miura
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Plastic Deformation ◽  
Basal Slip ◽  
Pure Shear ◽  
Mechanical Tests ◽  
Deformation Mechanisms ◽  
Solid Solution Alloy ◽  
Shear Stresses ◽  
Von Mises

ABSTRACTIn order to understand enhanced mechanical properties of magnesium-yttrium (Mg-Y) alloys, applied stresses which were required to operate independent plastic deformation mechanisms on various stress axes were evaluated. Moreover, for this analysis, mechanical tests including newly-established testing method “pure-shear test” were conducted to evaluate Critical Resolved Shear Stresses (CRSSes) for various plastic deformation mechanisms of Mg-Y solid solution alloy single crystals with various Y concentration. Relatively higher solid solution strengthening of dominant plastic deformation mechanisms such as basal slip and extension twin at room temperature, results in increase in the activation of non-basal slip system. By a simple analysis based on von-Mises criterion with experimental CRSS values, it is revealed that enhanced mechanical properties of Mg-Y alloys might be attributed to the decrease of difference in the activity of plastic deformation mechanisms by Y addition.

Experimental Evidence that the Onset of Mechanical Softening in Nanocrystalline Metals is Strain Rate Dependent

2009 ◽  
Vol 633-634 ◽  
pp. 99-105 ◽  
Author(s):  
Li Wei Wang ◽  
Barton C. Prorok
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Tensile Testing ◽  
Room Temperature ◽  
Applied Strain ◽  
Deformation Mechanisms ◽  
Strain Rates ◽  
Rate Dependent ◽  
Threshold Strain ◽  
Is Strain

This paper reports on the influence of strain rate on the onset of mechanical softening of nanocrystalline gold at room temperature. Micro-tensile testing was performed with applied strain rates on the order of 10−4 s−1 to 10−6 s−1. Our results defined a threshold strain rate, whereby plastic deformation at larger rates was dominated by dislocation processes and at smaller rates by one or more other deformation mechanisms.

scholarly journals Excellent ballistic impact resistance of Al0.3CoCrFeNi multi-principal element alloy with unique bimodal microstructure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saideep Muskeri ◽  
Bharat Gwalani ◽  
Shristy Jha ◽  
Anqi Yu ◽  
Philip A. Jannotti ◽  
...  
Keyword(s):  
Shear Bands ◽  
Stacking Faults ◽  
Adiabatic Shear ◽  
High Density ◽  
Deformation Mechanisms ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Bimodal Microstructure ◽  
Adiabatic Shear Bands ◽  
Principal Element

AbstractMulti-principal element alloys represent a new paradigm in structural alloy design with superior mechanical properties and promising ballistic performance. Here, the mechanical response of Al0.3CoCrFeNi alloy, with unique bimodal microstructure, was evaluated at quasistatic, dynamic, and ballistic strain rates. The microstructure after quasistatic deformation was dominated by highly deformed grains. High density of deformation bands was observed at dynamic strain rates but there was no indication of adiabatic shear bands, cracks, or twinning. The ballistic response was evaluated by impacting a 12 mm thick plate with 6.35 mm WC projectiles at velocities ranging from 1066 to 1465 m/s. The deformed microstructure after ballistic impact was dominated by adiabatic shear bands, shear band induced cracks, microbands, and dynamic recrystallization. The superior ballistic response of this alloy compared with similar AlxCoCrFeNi alloys was attributed to its bimodal microstructure, nano-scale L12 precipitation, and grain boundary B2 precipitates. Deformation mechanisms at quasistatic and dynamic strain rates were primarily characterized by extensive dislocation slip and low density of stacking faults. Deformation mechanisms at ballistic strain rates were characterized by grain rotation, disordering of the L12 phase, and high density of stacking faults.

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