Stress Evolution during Tensile Twinning in MgAZ31 Alloy Processed by Extrusion

2013 ◽  
Vol 773-774 ◽  
pp. 104-108
Author(s):  
K. Sitarama Raju ◽  
Peter A. Lynch ◽  
Matthew R. Barnett
Keyword(s):  
Lattice Strain ◽  
Volume Fraction ◽  
Peak Position ◽  
Stress Evolution ◽  
Axial Tension ◽  
Twin Nucleation ◽  
Peak Intensity ◽  
Diffraction Geometry ◽  
Linear Behaviour ◽  
Lattice Planes

An in-situ laboratory based X-ray diffraction technique has been developed to directly measure lattice strain and stress evolution associated with {10.2} < 10.1 > twin nucleation and growth in rolled and extruded Mg alloys during tensile loading. A transmission diffraction geometry was utilised to measure peak position and intensity for the (10.0), (00.2) and (10.1) lattice planes while the sample was loaded in uni-axial tension. Lattice re-orientation arising from deformation twinning is utilizedto estimate the twin volume fraction by measuring the increase in the (10.0) peak intensity along with a simultaneous decrease in the (00.2) peak intensity as a function of applied load. From observation of the lattice strain plotted against applied stress for different orientations it was found that the (10.1) orientation displayed the anticipated linear behaviour within the whole stress range. Yielding in the (10.2) and (10.3) orientations was identified at around 75 and 90 MPa respectively, indicating theonset of basal slip. Twin nucleation was observed at at a stress of approximately 110 MPa.

Non-Invasive Temperature Measurements by Neutron Diffraction in Aero-Engine Components

1994 ◽  
Vol 38 ◽  
pp. 9-20 ◽  
Author(s):  
T. M. Holden ◽  
J. H. Root ◽  
D. C. Tennant ◽  
D. Leggett
Keyword(s):  
Neutron Diffraction ◽  
Dynamic Test ◽  
Lattice Parameter ◽  
Peak Position ◽  
Intensity Measurements ◽  
Peak Intensity ◽  
High Penetration ◽  
Aeronautical Industry ◽  
Critical Components ◽  
Engine Components

Abstract A requirement exists in the aeronautical industry for measuring temperature non-invasively in critical components, such as the turbine disc in an operating engine. Neutron diffraction, unique among nuclear techniques, offers the possibility of measuring both temperature and strain within an operating engine by virtue of the high penetration of neutrons through industrial materials. Static diffraction experiments on Waspaloy and Ti6A14V showed, by comparison with thermocouples, that both the diffraction peak position and the peak intensity can measure the tempeiaturc to within ±6 K aL 800 K. Measurements on a rotating Waspaloy disc, heated from its rim, showed that temperature gradients could be determined accurately by lattice parameter measurements. The large grain size in Waspaloy prevented accurate peak intensity measurements in this dynamic test. Finally, the structures within a small Pratt &amp; Whitney engine in its equatorial plane were mapped by mounting the engine on an X-Y translator on the diffractometer and moving it through a grid of positions. Possible future directions in the field will be discussed.

Thickness-Dependent Optical Effects in Infrared Reflection-Absorption Spectra of a Fairly Thick Polymer Layer

2002 ◽  
Vol 56 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Marta KlanjšEk Gunde ◽  
Zorica Crnjak Orel
Keyword(s):  
Absorption Spectra ◽  
Normal Incidence ◽  
Peak Position ◽  
Mean Value ◽  
Absorption Bands ◽  
Medium Thickness ◽  
Peak Intensity ◽  
Infrared Reflection ◽  
Optical Effects ◽  
The Mean

Thickness-dependent intensities and positions of absorption lines in infrared reflection-absorption spectra of thin films on reflective substrates at near-normal incidence are investigated. Two types of absorption bands in a polymer, the weak and the strong, were examined. Their optical properties were determined by the dielectric response function. The optical path of the beam was described by the coherent sum of all successively reflected beams. The thickness-dependent properties of absorption bands were examined in three typical thickness regions. At small thickness, the peak intensity oscillates around the mean value defined by the simple internal absorptance of the beam crossing the double layer. For medium thickness, the peak position swings around the original frequency and its intensity oscillations move above the simple internal absorptance. In layers within the high-thickness region, optical distortions cause large changes in line shape due to approaching the bulk reflectance. A simple analytical interpretation is possible only within the low-thickness region. The width of these thickness regions depends on the absorptivity of the considered band; for strong bands they are considerably narrower than for weak bands. The theoretically predicted effects compare well with those measured in RAS spectra of variously thick silicon resin layers on aluminium substrates.

The Effect of Reinforcement Phase on the Microstructure of Al-SiC Nanocomposite Powder Prepared via Mechanical Alloying

2009 ◽  
Vol 83-86 ◽  
pp. 764-770
Author(s):  
Taha Rostamzadeh ◽  
H. Shahverdi ◽  
R. Sarraf-Mamoory ◽  
A. Shanaghi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Metal Matrix ◽  
Milling Time ◽  
Lattice Strain ◽  
Volume Fraction ◽  
Aluminum Matrix ◽  
High Energy ◽  
Nanocomposite Powder ◽  
Nanocomposite Powders

Mechanical alloying is one of the most successful methods for the manufacturing of metal matrix nanocomposite powders. In this study, Al/SiC metal matrix composite (MMCp) powders with volume fractions of 5, 10, and 15 percent SiC were successfully obtained after milling the powder for a period of 25 hours at a ball to powder ratio of 15:1 using high energy planetary milling. The Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were conducted to investigate the lattice strain of the matrix phase and the microstructure of the nanocomposite powders after 1, 10, and 25 hours of milling time. Also, the morphology of the Al-5%SiC nanocomposite powder was investigated using transmission electron microscopy (TEM). The results show that with the increase of both milling time and the reinforcement phase volume fraction, the lattice strain increases and the average size of aluminum phase crystallites decreases. Eventually, after 25 hours of milling, the nanocomposite powders show a spherical-like morphology and SiC particles were distributed in an aluminum matrix with appropriate order.

Elongational Viscosities of Polymethylmethacrylate / Nano-Clay Composites

2007 ◽  
Vol 17 (5) ◽  
pp. 52751-1-52751-9 ◽  
Author(s):  
Nikolaos Katsikis ◽  
Tobias Königer ◽  
Helmut Münstedt
Keyword(s):  
Volume Fraction ◽  
Constant Strain Rate ◽  
Clay Content ◽  
Elongational Flow ◽  
Zero Shear Viscosity ◽  
Softening Behavior ◽  
Transmission Electron ◽  
Nano Clay ◽  
Linear Behaviour ◽  
Means Of Transmission

Abstract The elongational flow of polymethylmethacrylate / nano-clay composites was studied during stressing and creep experiments using a Münstedt tensile rheometer (MTR). The dispersion of the nano-clay was controlled by means of transmission electron microscopy (TEM) and the layer distance was measured with X-ray diffraction (XRD). With growing volume fraction of the filler an increase of the viscosity is observed under constant strain rate and constant stress conditions. The results for the elongational viscosities for both modes are consistent with each other. Furthermore, a strain softening behavior can be measured, which is the more pronounced the higher the nano-clay content is. As the Trouton rule is not valid, deviations from the linear behaviour are related to an envolope curve for the elongational viscosities instead of the threefold zero shear viscosity.

RAMAN AND PEELS STUDIES ON MAGNETRON SPUTTERED a-C

2000 ◽  
Vol 14 (02n03) ◽  
pp. 268-273 ◽  
Author(s):  
SAM ZHANG ◽  
TAN MING JEN ◽  
XIANTING ZENG ◽  
HONG XIE ◽  
PETER HING
Keyword(s):  
Amorphous Carbon ◽  
Peak Position ◽  
Carbon Films ◽  
Nitrogen Atmosphere ◽  
Peak Intensity Ratio ◽  
Carbon Coatings ◽  
Peak Intensity ◽  
Wafer Substrate ◽  
Amorphous Carbon Coatings ◽  
Electron Energy Loss

Amorphous carbon coatings (a-C, a-C:H) of less than 100 nm thick were deposited on KBr pellets and silicon wafer substrate via magnetron sputtering of graphite target in argon, argon/hydrogen and argon/nitrogen atmosphere. Parallel electron energy loss spectroscopy (PEELS) analysis was used to quantify the sp 2/ sp 3 bonding in carbon films. Stand-alone films of amorphous carbon were produced by sputtering onto compressed KBr pellets and then floating off is distilled water for PEELS study. Raman spectroscopy was used to measure the peak intensity ratio of D-band to that of the G-band (IdIg). It shows that higher sp 3 fraction often associates with lower Raman peak ratio (IdIg). At the same time, G-band peak position P g decreases while sp 3 fraction increases.

Structural Relaxation and Interdiffusion in Amorphous Fe-Ti Compositionally Modulated Films

1986 ◽  
Vol 80 ◽  
Author(s):  
Eric H. Chason ◽  
Tadashi Mizoguchi
Keyword(s):  
Free Volume ◽  
Structural Relaxation ◽  
Peak Position ◽  
Relaxation Kinetics ◽  
X Ray ◽  
Volume Model ◽  
Peak Intensity ◽  
Free Volume Model ◽  
Kinetics Of

AbstractInterdiffusion and structural relaxation in amorphous compositionally modulated films of Fe-Ti have been measured simultaneously. Interdiffusivity is determined by the change in X-ray modulation peak intensity upon annealing and structural relaxation is determined by the shift in X-ray peak position corresponding to the densification. The relaxation kinetics of the densification are explained by the free volume model of structural relaxation. The relaxation kinetics of the inverse diffusivity are shown to be the same as for viscosity relaxation.

Non-Destructive Quantitative Phase and Residual Stress Analysis Versus Depth Using Grazing X-Ray Diffraction

2007 ◽  
Vol 130 ◽  
pp. 47-52 ◽  
Author(s):  
S.J. Skrzypek ◽  
M. Goły ◽  
Wiktoria Ratuszek ◽  
Mieczyslaw Kowalski
Keyword(s):  
Residual Stresses ◽  
Phase Analysis ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Ball Bearings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quantitative Phase ◽  
Diffraction Geometry ◽  
Non Destructive

The non-destructive structure characterisation of surface layers for various kinds of ball bearings can be a powerful method in surface characterization and in quality control. The ball bearings were made of 100Cr6 steel and they were superfinished and mechanically burnished. An application of classical X-ray diffraction sin2ψ method and classical Bragg-Brentano diffraction geometry in these kinds of surface examinations make some problems in term of X-ray real depth of penetration. An application of methods based on grazing angle X-ray diffraction geometry, made possible to get real value of residual macro-stresses, retained austenite and additionally could be suitable in estimation of their gradient-like distribution versus depth under surface. An application of this geometry to X-ray diffraction phase analysis enabled to get phase contents versus thickness under surface in non-destructive way as well. The results are not infected by gradient-like distribution. The X-ray quantitative phase analysis was used to establish volume fraction of transformed retained austenite. Theoretical calculation of residual macro-stresses due to volume fraction of transformed austenite in ball bearings and following measurements of residual stresses were curried out as well. The mechanical burnishing of ball bearings caused big compressive residual stresses about – 1000 MPa and phase transformation of austenite in thin surface layer. These factors can influence on properties of following exploitation and durability.

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