In Situ Synchrotron Analysis of Twinning Stresses in an Aged Mg-4.5Zn Alloy

2018 ◽  
Vol 941 ◽  
pp. 1579-1584 ◽  
Author(s):  
Mahmoud Reza Ghandehari Ferdowsi ◽  
Jun Wang ◽  
Sitarama R. Kada ◽  
Zhi Yang Wang ◽  
Peter A. Lynch ◽  
...  
Keyword(s):  
Yield Strength ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Aged Condition ◽  
X Ray ◽  
Peak Broadening ◽  
Strong Relation ◽  
Twin Volume Fraction ◽  
Zn Alloys

Aging increases the yield strength of aged Mg-Zn alloys. The effect of aging on the stress required for twinning is examined using in-situ transmission based synchrotron X-ray diffraction. The as extruded material was aged at variety of temperatures for different times. It is found that increasing sample diameter (thickness) results in peak broadening. The data are analysed to establish the evolution of twin volume fraction with stress. Results indicated an increase in twinning stress at 10% twin volume fraction in aged samples in comparison with non-aged condition. The investigation showed a strong relation between the macroscopic yield stress and the twinning stress (at 10% twin volume fraction).

scholarly journals In Situ X-Ray Diffraction during Casting: Study of Hot Tearing in Al-Zn Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1134-1141 ◽  
Author(s):  
Jean Marie Drezet ◽  
Bastien Mireux ◽  
Guven Kurtuldu
Keyword(s):  
Volume Fraction ◽  
Solid Phase ◽  
Hot Spot ◽  
Solid Volume Fraction ◽  
Internal Stresses ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zn Alloys

During solidification of metallic alloys, coalescence corresponds to the formation of solid bridges between grains when both solid and liquid phases are percolated. As such, it represents a key transition with respect to the mechanical behaviour of solidifying alloys and to the prediction of solidification cracking. Coalescence starts at the coherency point when the grains begin to touch each other, but are unable to sustain any tensile loads. It ends up at the rigidity temperature when the solid phase is sufficiently coalesced to transmit macroscopic tensile strains and stresses. This temperature, also called mechanical or tensile coherency temperature, is a major input parameter in numerical modelling of solidification processes as it defines the point at which thermally induced deformations start to generate internal stresses in a casting. The rigidity temperature has been determined in Al Zn alloys using in situ X-ray diffraction (XRD) during casting in a dog bone shaped mould. This set-up allows the sample to build up internal stress naturally as its contraction is prevented. The cooling on both extremities of the mould induces a hot spot at the middle of the sample which is irradiated by X-rays. Diffraction patterns were recorded every 0.5 s using a detector covering a 426 x 426 mm2area. The change of diffraction angles allowed us to observe agglomeration/decohesion of growing grain clusters and to determine a solid volume fraction at rigidity around 98 % depending on solidification time for grain refined Al 6.2 wt% Zn alloys.

scholarly journals Measurement of Mechanical Coherency Temperature and Solid Volume Fraction in Al-Zn Alloys Using In Situ X-ray Diffraction During Casting

2015 ◽  
Vol 46 (9) ◽  
pp. 4183-4190 ◽  
Author(s):  
Jean-Marie Drezet ◽  
Bastien Mireux ◽  
Güven Kurtuldu ◽  
Oxana Magdysyuk ◽  
Michael Drakopoulos
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coherency Temperature ◽  
Zn Alloys

Microstructure and Mechanical Properties of In Situ TiB2/6061 Composites

2012 ◽  
Vol 535-537 ◽  
pp. 14-17
Author(s):  
Long Hua Zhong ◽  
Yu Tao Zhao ◽  
Song Li Zhang ◽  
Rong Wen
Keyword(s):  
Master Alloy ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Melt Mixing ◽  
X Ray ◽  
Mixing Method ◽  
Particulate Volume Fraction ◽  
Ti Powder ◽  
Particulate Volume

In situ TiB2/6061 composites have been successfully synthesized through chemical reaction between 6061 master alloy, Al-3B master alloy and Ti powder. The composites fabricated by direct melt mixing method was investigated by Scanning Electron Microscope (SEM), Energy Dispersive x-ray Spectroscopy (EDS) and X-Ray Diffraction (XRD), The results shown the existence of TiB2particles. The size of most TiB2particles were just in micron level, and even reached to sub-micron level. The increase in microhardness and tensile strength for the as-prepared composites with 5% particulate volume fraction (PVF) are up to 26.8% and 51.2% respectively.

In situ x-ray observation of bainitic transformation of austempered silicon alloyed steel

2009 ◽  
Vol 24 (4) ◽  
pp. 1559-1566 ◽  
Author(s):  
Xiang Chen ◽  
Esa Vuorinen
Keyword(s):  
Volume Fraction ◽  
Early Stage ◽  
Bainitic Ferrite ◽  
Bainitic Transformation ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Heterogeneous Distribution ◽  
X Ray ◽  
Austempering Temperature

The in situ x-ray diffraction observations of the bainitic transformation were conducted by using the high-temperature x-ray diffraction technique. The volume fraction and carbon content of austenite depend on the transformation temperature. The d{110} value of bainitic ferrite decreases with increasing austempering temperature, which is related to the decrease of carbon concentration in bainitic ferrite. Asymmetry diffraction peaks are obtained for samples at the early stage of transformation at any austempering temperatures. This asymmetry diffraction peak after the formation of bainitic ferrite could be attributed to a heterogeneous distribution of carbon in different regions of austenite and show that two types of austenite with different carbon contents, low-carbon austenite (γLC) and the high-carbon austenite (γHC), exist during the transformation. The microstructure after cooling down to room temperature is presented to show the effectiveness of the x-ray diffraction analysis.

Evaluation of Tri-Axial Magnetostriction in Cube-Oriented Fe-Ga Single Crystal by Using X-Ray Diffraction Method

2017 ◽  
Vol 909 ◽  
pp. 300-305 ◽  
Author(s):  
Takehito Ikeuchi ◽  
Akihiro Koyama ◽  
Muneyuki Imafuku ◽  
Shun Fujieda ◽  
Yusuke Onuki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Volume Fraction ◽  
Diffraction Method ◽  
Diffraction Measurement ◽  
Magnetic Field Direction ◽  
Magnetic Domains ◽  
X Ray Diffraction ◽  
X Ray

We carried out in situ tri-axial magnetostriction analysis for cube-oriented Fe-18%Ga single crystal by X-ray diffraction measurement under magnetic field. Periodic change in tri-axial magnetostriction with applied magnetic field direction was clearly observed. However, those values in [100] and [010] directions were not equivalent. Theoretical calculation of magnetostriction considering domain structure revealed this is caused by the non-equivalent volume fraction of initial magnetic domains.

Microstructure of In Situ Particles/7055Al Matrix Composites with Deep Cryogenic Treatment

2012 ◽  
Vol 217-219 ◽  
pp. 114-118 ◽  
Author(s):  
Xun Yin Zhang ◽  
Gui Rong Li ◽  
Ting Wang Zhang ◽  
Lei Cao ◽  
Hong Ming Wang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Cryogenic Treatment ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Deep Cryogenic Treatment ◽  
X Ray ◽  
Diffraction Peaks

Al2O3，Al3Ti and Al3Zr particles reinforced 7055 aluminium matrix composites were fabricated via melt reaction method. The volume fraction is controlled at about 4-5%. After extrusion and solution-aging heat treatment the sample was prepared for deep cryogenic treatment, The microstructure and evolution of mechanical properties of (Al3Ti+Al3Zr)p/7055 composites were analyzed using optical microscopy(OM),scanning electronic microscopy(SEM) and X-ray diffraction(XRD). Some θ(Al2Cu) phases with nanometer size precipitate in the inner grain. As some grains preferred orient the intensity of some main diffraction peaks increase. Compared with those of as-cast and squeezed states the micro hardness has increased by 16.8% and 10.0% separately.

In-Situ Studies of Silicide Formation in Ti-Ta Bilayer Thin Films on Poly-Si

2002 ◽  
Vol 721 ◽  
Author(s):  
A. S. Özcan ◽  
K. F. Ludwig ◽  
C. Lavoie ◽  
C. Cabral ◽  
J. M. E. Harper
Keyword(s):  
Volume Fraction ◽  
Formation Temperature ◽  
Silicide Formation ◽  
X Ray Diffraction ◽  
Template Effect ◽  
Elastic Light Scattering ◽  
Time Resolved ◽  
X Ray ◽  
Si Substrates

AbstractWe have studied the formation of titanium silicides in the presence of an ultra-thin layer of Ta, interposed between Ti and Si. In-situ x-ray diffraction (XRD), resistance measurements and elastic light scattering were used to study the thin film reactions in real time during ramp anneals to 1000°C. On poly-Si substrates the Ta thickness was varied from 0 to 1.5 nm while the Ti thickness was held constant at ∼27 nm. The time-resolved XRD shows that the volume fraction of C40 and metal-rich silicide phases grows with increasing Ta layer thickness. Increased Ta layer thicknesses also delay the growth of the C49 disilicide phase to higher temperatures. Among the Ta thicknesses we examined, 0.3 nm is the most effective in lowering the C49-C54 transformation temperature. Films with Ta layers thicker than 0.5 nm do not completely transform into the C54 phase. The texture of the C54 phase is also sensitive to the Ta thickness. The C54 disilicide film is predominantly (010) textured for the Ti / 0.3 nm Ta sample. The final C54 texture is significantly different for Ta layers thinner or thicker than the optimal 0.3 nm. This suggests that the most effective thickness for lowering the C54 formation temperature is related to the development of a strong (010) texture. The possibility of a template effect by the C40 or metal-rich Ti5Si3 phases is also discussed on the basis of texture considerations.

An In Situ High-Temperature X-Ray Diffraction Study of Phase Transformations in Maraging 300 Steel

2017 ◽  
Vol 371 ◽  
pp. 73-77 ◽  
Author(s):  
Adriano Gonçalves Reis ◽  
Danieli Aparecida Pereira Reis ◽  
Antônio Jorge Abdalla ◽  
Antônio Augusto Couto ◽  
Jorge Otubo
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Austenite Transformation ◽  
X Ray ◽  
Xrd Diffraction ◽  
Temperature Solution ◽  
Diffraction Patterns

An in situ high-temperature X-ray diffraction (HTXRD) study in maraging 300 steel was carried out to study the martensite to austenite transformation and effect of time of exposure in the austenite reversion below austenite start temperature. Solution annealed materials were subjected to controlled heating-holding cycles. The first sample was heated at a rate of 10 oC/min from room temperature to 800 oC, showing that the microstructure is completely martensitic (α’110) until 600 oC. From 650 oC until 800 oC, the microstructure is gradually changing from martensitic to austenitic, showed by the increasing peaks of γ111 and reducing peaks of α’110. At 800 oC the microstructure is completely austenitic (γ111). Another sample was heated at 10 oC/min from room temperature to 600 oC and held for 4 hours. At 600 oC, at 0 h time of exposure, only a martensitic peak was observed. An austenite peak can be observed after some time of exposure at this temperature. The volume fraction of austenite increased with increasing time of exposure at 600 oC, reaching 50/50 volume fraction after 4 hours of exposure. XRD diffraction patterns for the same sample that was held for 4 hours at 600 oC and then cooled down in air to room temperature showed the same intensity of austenite and martensitic peaks found in situ at 600 oC for 4 hours (retained austenite), with the volume fraction of 50/50 of austenite and martensite phases. The HTXRD technique can be used to identify and quantify martensite to austenite transformation and austenite retention.

scholarly journals In Situ High Temperature X-Ray Studies on Bainitic Transformation of Austempered Silicon Alloyed Steels

2010 ◽  
Vol 638-642 ◽  
pp. 3086-3092 ◽  
Author(s):  
Esa Vuorinen ◽  
Xiang Chen
Keyword(s):  
High Temperature ◽  
Volume Fraction ◽  
Early Stage ◽  
Bainitic Transformation ◽  
Experimental Results ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Heterogeneous Distribution ◽  
X Ray

The in-situ X-ray diffraction observations of the bainitic transformation of silicon alloyed steels were performed using the high temperature X-ray diffraction technique. The experimental results have shown that the volume fraction and carbon content of austenite remains a constant value which indicate that the transformation is almost finished after the early stages of austempering transformation. Asymmetry diffraction peaks are obtained for samples at the early stage of transformation due to a heterogeneous distribution of carbon in different regions of austenite and thus exists two types of austenite: low-carbon austenite (γLC) and the high-carbon austenite (γHC). The experimental results supports that the bainite growth is by a non-diffusive mechanism when austempering temperature is in the lower bainite transformation temperature.

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