scholarly journals Study on the Mechanism and Application of Applying Magnetic Barkhausen Noise to Evaluate Dislocation Density and Plastic Deformation

2020 ◽  
Author(s):  
Xueliang Kang ◽  
Shiyun Dong ◽  
Hongbin Wang ◽  
Xiaoting Liu ◽  
Shixing Yan
Keyword(s):  
Plastic Deformation ◽  
Dislocation Density ◽  
Diffraction Method ◽  
Grain Morphology ◽  
Barkhausen Noise ◽  
Magnetic Barkhausen Noise ◽  
X Ray Diffraction ◽  
X Ray ◽  
Texture Characteristics ◽  
Residual Strains

Seven specimens of 45 steel with different residual strains were prepared by homogeneous plastic tensile test. The microstructure of the specimens was observed by scanning electron microscopy and the texture characteristics of the specimens were studied by X-ray diffraction. The results showed that plastic deformation mainly leads to dislocation increment in the microstructure rather than obvious deformed grain morphology, texture and residual stress. Then the dislocation density of each sample was calculated by X-ray diffraction method. The MBN signals of the samples were tested by magnetic Barkhausen noise method and the corresponding RMS (root mean square) values were calculated. The results showed that the dislocation density increases and the RMS value decreases with the increase of plastic deformation magnitude, the phenomenon was explained deeply. By establishing the correlation between dislocation density and RMS value, it was found that there was a good linear relationship between dislocation density and RMS value. According to the formula provided by the fitting curve, the dislocation density can be predicted by measuring the RMS value of any degree of plastic deformation.

Study of Machining-Induced Microstructure Variations of Nanostructured/Ultrafine-Grained Copper Using XRD

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Yong Huang ◽  
Mason Morehead
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Dislocation Density ◽  
Equal Channel Angular Extrusion ◽  
Outer Radius ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Area And Volume

Various methods for the production of bulk nanostructured (NS)/ultrafine-grained (UFG) materials have been developed, including equal channel angular extrusion (ECAE), a form of severe plastic deformation. Using an ECAE NS/UFG copper bar as an example, this study has investigated machining-induced workpiece microstructure variation using X-ray diffraction. It has been found that (1) under gentle cutting conditions, there was a 10% increase in the median grain size compared with unmachined ECAE NS/UFG copper bars. Increases in the arithmetic-, area-, and volume-weighted grain sizes were found to be 10%, 8%, and 8%, respectively, and (2) an average 27% drop in the dislocation density was observed between the machined and unmachined ECAE copper bars. The dislocation density was shown to have the most reduction (−39%) at the outer radius of the machined ECAE bar where more heat and/or higher pressure were experienced.

Development of High Performance Magnesium Alloys via Microstructure and Texture Control

2009 ◽  
Vol 618-619 ◽  
pp. 249-252 ◽  
Author(s):  
Jung Woo Choi ◽  
Kwang Seon Shin
Keyword(s):  
Plastic Deformation ◽  
High Performance ◽  
Deformation Behaviour ◽  
Extrusion Direction ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Al Content ◽  
Deformation Modes ◽  
Compressive Tests

The mechanical properties of extruded ZA (Mg-Zn-Al) alloys with different Al contents were examined. The effects of Al on deformation behaviour were examined by tensile and compressive tests. The changes in texture due to plastic deformation were examined using the X-ray diffraction method. It was found that the basal poles of the extruded ZA alloy were parallel to the normal direction with a slight tendency to incline toward the extrusion direction. The degree of inclination increased with increasing Al content. The inclination degree of the basal poles was found to be closely related to the change in the deformation behaviour of the ZA alloy. Computer simulations were also carried out using the VPSC (visco-plastic self-consistent) theory in order to predict the contributions of various deformation modes to the plastic deformation behaviour of the ZA alloy.

High Density Dislocation and Magnetoplasticity in Nano-Sized Alumina Reinforced 7055Al Composites Subject to High Magnetic Field

2014 ◽  
Vol 941-944 ◽  
pp. 462-465
Author(s):  
Guirong Li ◽  
Hong Ming Wang ◽  
Pei Si Li ◽  
Rui Zheng ◽  
Yue Ming Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
High Magnetic Field ◽  
High Density ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
X Ray ◽  
Transmission Electronic Microscopy

Nanometer Al2O3 particles reinforced 7055Al composites were processed by high magnetic field with 2T,3T and 4T magnetic induced intensity (B) with constant 30 pulses. Transmission Electronic Microscopy (TEM) and X ray diffraction (XRD) were mainly used to analyze some characteristic of the treated samples. The results show that with the increase of B the dislocation density was enhanced apparently. It is deduced that plastic deformation was the main reason of high density dislocation. The magnetoplasticity effect was the source of plastic deformation.

INVESTIGATION OF CYCLIC SOFTENING BEHAVIOR OF SHOT PEENED S30432 AUSTENITIC STAINLESS STEEL BY X-RAY DIFFRACTION METHOD

2014 ◽  
Vol 21 (06) ◽  
pp. 1450076 ◽  
Author(s):  
KE ZHAN ◽  
XUE JUN ZHENG ◽  
HAO HAN ◽  
QIANG FENG ◽  
CHUAN HAI JIANG
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Dislocation Density ◽  
Diffraction Method ◽  
Cyclic Softening ◽  
External Loading ◽  
Strengthening Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Softening Behavior

Microstructure evolution of shot peened S30432 austenitic stainless steel under external loading was investigated by X-ray diffraction method. The domain size, micro-strain, and dislocation density were calculated by Voigt method and Williamson method, respectively. The results show that the dislocation density decreases sharply in initial stage, then undergoes a stable stage, following by an increase in the end. It reveals that cyclic softening happened during cyclic loading, and it can ascribe to the high dislocation density after shot peening (SP). This study suggests that cyclic softening behavior may need to take into consideration when considering the strengthening effect of SP.

Depth Dependence of Residual Strains in Textured Mo Thin Films Using High-Resolution X-Ray Diffraction

1995 ◽  
Vol 403 ◽  
Author(s):  
S. G. Malhotra ◽  
Z. U. Rek ◽  
S. M. Yalisove ◽  
J. C. Bilello
Keyword(s):  
High Resolution ◽  
Diffraction Method ◽  
Growth Direction ◽  
Elastic Model ◽  
Normal Strain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Depth Dependence ◽  
Residual Strains ◽  
Film Substrate

AbstractThe magnitude of the average stress in a thin film can be obtained by measuring the curvature of the film-substrate couple. However, the details of the strain distribution, as a function of depth through the thickness of the film, can have important consequences in governing film quality and ultimate morphology. A high-resolution x-ray diffraction method was used to determine the depth dependence of strain in a textured Mo film, with a nominal thickness of 260 nm, which was deposited by planar magnetron sputtering onto Si (100) substrates. The principal strains, resolved onto a laboratory reference frame, displayed a negligible gradient in the azimuthal directions (x and y), but displayed a large gradient in the direction normal to the film (z). A similar trend was previously observed for a 100 nm polycrystalline film, but the magnitude of the normal strain very near the free surface was about a factor of 2 less. The increase in the normal strain may be due to the development of a preferred growth direction and grain facetting. A linear elastic model was also used to determine the strains in successive slabs of the film, where strain variations between slabs were indicated.

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

scholarly journals Study of Corrosion Resistance and Degradation Mechanisms in LiTiO2-Li2TiO3 Ceramic

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 753
Author(s):  
Dmitriy Shlimas ◽  
Artem L. Kozlovskiy ◽  
Maxim Zdorovets
Keyword(s):  
Degradation Mechanism ◽  
Diffraction Method ◽  
Large Mass ◽  
Time Frame ◽  
X Ray Diffraction ◽  
Acidic Media ◽  
X Ray ◽  
Mass Losses ◽  
The Stability ◽  
Thermal Sintering

The interest in lithium-containing ceramics is due to their huge potential as blanket materials for thermonuclear reactors for the accumulation of tritium. However, an important factor in their use is the preservation of the stability of their strength and structural properties when under the influence of external factors that determine the time frame of their operation. This paper presents the results of a study that investigated the influence of the LiTiO2 phase on the increasing resistance to degradation and corrosion of Li2TiO3 ceramic when exposed to aggressive acidic media. Using the X-ray diffraction method, it was found that an increase in the concentration of LiClO4·3H2O during synthesis leads to the formation of a cubic LiTiO2 phase in the structure as a result of thermal sintering of the samples. During corrosion tests, it was found that the presence of the LiTiO2 phase leads to a decrease in the degradation rate in acidic media by 20–70%, depending on the concentration of the phase. At the same time, and in contrast to the samples of Li2TiO3 ceramics, for which the mechanisms of degradation during a long stay in aggressive media are accompanied by large mass losses, for the samples containing the LiTiO2 phase, the main degradation mechanism is pitting corrosion with the formation of pitting inclusions.

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