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.

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.

scholarly journals Deformation Microstructures and Textures of Cast Mg-3Sn-2Ca Alloy under Uniaxial Hot Compression

2012 ◽  
Vol 152-154 ◽  
pp. 322-325
Author(s):  
C. Dharmendra ◽  
K.P. Rao ◽  
Y.V.R.K. Prasad ◽  
N. Hort ◽  
K.U. Kainer
Keyword(s):  
Factor Analysis ◽  
Crystallographic Orientation ◽  
Basal Slip ◽  
Texture Evolution ◽  
Hot Compression ◽  
Strain Rates ◽  
Slip Systems ◽  
Schmid Factor ◽  
Orientation Information ◽  
Cylindrical Samples

The influence of deformation conditions on the microstructure and texture evolution during hot compression of Mg-3Sn-2Ca (TX32) has been studied. Cylindrical samples were compressed uniaxially at different combinations of temperatures and strain rates in the ranges 300-500 oC and 0.0003-10 s-1. The crystallographic orientation information of the as-cast and deformed specimens was obtained by EBSD micro-texture analysis. Activation of different slip systems was investigated using Schmid factor analysis and the results reinforce the importance of non-basal slip for deformation at high temperatures. Samples deformed at 500 oC/0.1 s-1 resulted in a fully recrystallized microstructure with near random crystallographic texture.

The Effect of Secondary Metalworking Processes on Susceptibility of Aircraft to Catastrophic Failures and Prevention Methods

2013 ◽  
Vol 58 (4) ◽  
pp. 1207-1212
Author(s):  
E.S. Dzidowski
Keyword(s):  
Dynamic Recovery ◽  
Fatigue Cracks ◽  
Shear Bands ◽  
Adiabatic Shear ◽  
Deformation Mechanisms ◽  
Processing Maps ◽  
Adiabatic Shear Bands ◽  
Flow Localization ◽  
Catastrophic Failures ◽  
Prevention Methods

Abstract The causes of plane crashes, stemming from the subcritical growth of fatigue cracks, are examined. It is found that the crashes occurred mainly because of the negligence of the defects arising in the course of secondary metalworking processes. It is shown that it is possible to prevent such damage, i.e. voids, wedge cracks, grain boundary cracks, adiabatic shear bands and flow localization, through the use of processing maps indicating the ranges in which the above defects arise and the ranges in which safe deformation mechanisms, such as deformation in dynamic recrystallization conditions, superplasticity, globularization and dynamic recovery, occur. Thanks to the use of such maps the processes can be optimized by selecting proper deformation rates and forming temperatures.

Deformation mechanisms of basal slip, twinning and non-basal slips in Mg-Y alloy by micropillar compression

2021 ◽  
pp. 141408
Author(s):  
Na Li ◽  
Lingwei Yang ◽  
Chuanyun Wang ◽  
M.A. Monclús ◽  
Dongfeng Shi ◽  
...  
Keyword(s):  
Basal Slip ◽  
Deformation Mechanisms ◽  
Micropillar Compression

scholarly journals Effect of High Strain Rate on Adiabatic Shearing of α+β Dual-Phase Ti Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2044
Author(s):  
Fang Hao ◽  
Yuxuan Du ◽  
Peixuan Li ◽  
Youchuan Mao ◽  
Deye Lin ◽  
...  
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Damage Tolerance ◽  
Shear Bands ◽  
Dual Phase ◽  
Ti Alloy ◽  
Hopkinson Pressure Bar ◽  
Β Phase ◽  
Schmid Factor ◽  
Pressure Bar

In the present work, the localized features of adiabatic shear bands (ASBs) of our recently designed damage tolerance α+β dual-phase Ti alloy are investigated by the integration of electron backscattering diffraction and experimental and theoretical Schmid factor analysis. At the strain rate of 1.8 × 104 s−1 induced by a split Hopkinson pressure bar, the shear stress reaches a maximum of 1951 MPa with the shear strain of 1.27. It is found that the α+β dual-phase colony structures mediate the extensive plastic deformations along α/β phase boundaries, contributing to the formations of ASBs, microvoids, and cracks, and resulting in stable and unstable softening behaviors. Moreover, the dynamic recrystallization yields the dispersion of a great amount of fine α grains along the shearing paths and in the ASBs, promoting the softening and shear localization. On the contrary, low-angle grain boundaries present good resistance to the formation of cracks and the thermal softening, while the non-basal slipping dramatically contributes to the strain hardening, supporting the promising approaches to fabricate the advanced damage tolerance dual-phase Ti alloy.

Compressive Plasticity of Zr-Based Bulk Metallic Glass at Low Temperature

2012 ◽  
Vol 443-444 ◽  
pp. 583-586
Author(s):  
Ya Juan Sun ◽  
Ri Ga Wu ◽  
Hong Jing Wang
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Low Temperatures ◽  
Room Temperature ◽  
Shear Bands ◽  
Strain Curve ◽  
Testing Temperature ◽  
Stress Strain Curve

The mechanical properties of a new Zr-based bulk metallic glass at low temperatures were investigated. The results indicate that the fracture strength increases significantly (4.9%) and the global plasticity increases somewhat when testing temperature is lowered to 123K. The stress-strain curve of the sample deformed exhibits more serrations and smaller stress drop due to formation of more shear bands at low temperature than at room temperature.

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