Heat Treatment of Cast and Cold Rolled Al–Yb and Al–Mn–Yb–Zr Alloys

The microstructure, electrical properties and microhardness of as-cast and cold rolled AlYb and AlMnYbZr alloys were investigated. The addition of Mn, Yb and Zr has a positive influence on grain size. A deformed structure of the grains with no changes of their size was observed after cold rolling. The Al3Yb particles coherent with the matrix were observed in the AlYb alloys. The size of the particles was about 20 nm in the initial state; after isochronal treatment up to 540 °C the particles coarsen, and their number density was lower. The deformation has a massive effect on the microhardness behavior until treatment at 390 °C, after which the difference in microhardness changes between as-cast and cold rolled alloys disappeared. Relative resistivity changes show a large decrease in the temperature interval of 330–540 °C which is probably caused by a combination of recovery of dislocations and precipitation of the Al3(Yb,Zr) particles. Precipitation hardening was observed between 100 and 450 °C in the AlYb alloy after ageing at 625 °C/24 h and between 330 and 570 °C in the AlMnYbZr alloy after ageing at 625 °C/24 h.

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Transmission Kossel Study of the Structure of Cold-Rolled Iron and its Nucleation Behaviour

Texture of Crystalline Solids ◽

10.1155/tsm.2.143 ◽

1977 ◽

Vol 2 (3) ◽

pp. 143-168 ◽

Cited By ~ 10

Author(s):

Y. Inokuti ◽

R. D. Doherty

Keyword(s):

Deformation Band ◽

Boundary Migration ◽

Rolling Plane ◽

Deformation Bands ◽

Thin Sections ◽

Nucleation Mode ◽

Grain Formation ◽

The Matrix ◽

Cold Rolled ◽

The Difference

By examining thin sections and by use of the more strongly absorbed Ti Kα radiation rather than Fe Kα radiation it was found possible to obtain useful transmission Kossel patterns from iron that had been deformed 40% by rolling. Examination of the as–deformed material showed large misorientations in all the matrix grains (20–54°) and many of the grains showed deformation bands where the orientation changed rapidly (up to 15° over distances of 50 μm). On annealing the material recrystallized by strain-induced boundary migration with all the invaded grains being those with (111) parallel to the rolling plane. Only one example was found of new grain formation by mutual invasion across a deformation band, the main nucleation mode previously observed in aluminum deformed 40% by compression. The difference between the two examples appears to arise from the smaller misorientations of the deformation bands in rolled iron.

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Experimental and Computational Studies of Competitive Precipitation Behavior Observed in Microstructures with High Dislocation Density and Ultra-Fine Grains

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.1787 ◽

2012 ◽

Vol 706-709 ◽

pp. 1787-1792 ◽

Cited By ~ 5

Author(s):

Tetsuya Masuda ◽

Shoichi Hirosawa ◽

Z. Horita ◽

Kenji Matsuda

Keyword(s):

Dislocation Density ◽

Precipitation Hardening ◽

Volume Fraction ◽

High Dislocation Density ◽

Nucleation Theory ◽

Precipitation Behavior ◽

The Matrix ◽

Deformation Processes ◽

Cold Rolled ◽

Good Agreement

The competitive precipitation behavior observed in microstructures with high dislocation density and ultra-fine grains has been studied experimentally and computationally for cold-rolled and severe plastic deformed Al-Mg-Si alloy. The age-hardenability at 443K was reduced by the two deformation processes due to the accelerated formation of larger precipitates on dislocations and grain boundaries, in place of the transgranular precipitation of refined β” in the matrix. The developed numerical model based on the classical heterogeneous nucleation theory clarified the dislocation density and grain size dependences of the volume fraction of precipitates nucleated at different sites, in good agreement with experimental results. It could be therefore possible that three strengthening mechanisms of strain hardening, hardening by grain refinement and precipitation hardening are optimally exploited according to the computationally estimated dependences.

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Carbide Precipitation in a Low Alloyed Steel during Aging Studied by Atom Probe Tomography and Thermodynamic Modeling

Metals ◽

10.3390/met11122009 ◽

2021 ◽

Vol 11 (12) ◽

pp. 2009

Author(s):

Mattias Thuvander ◽

Hans Magnusson ◽

Ulrika Borggren

Keyword(s):

Atom Probe Tomography ◽

Precipitation Hardening ◽

Atom Probe ◽

Carbide Precipitation ◽

Martensitic Structure ◽

Number Density ◽

High Number Density ◽

Molybdenum Carbides ◽

The Matrix ◽

Low Alloyed Steel

Carbide precipitation in martensitic low alloyed steels contributes to the mechanical properties through precipitation hardening. A high number density of carbides is desired to maximize the hardening effect, which is achieved through the precipitation of carbides on the dislocations in the martensitic structure. In this study, the nucleation, growth, and coarsening of vanadium and molybdenum carbides during aging at 600 °C for periods up to four weeks were investigated. The work covers characterization with atom probe tomography, which showed that the nucleation of V and Mo rich MC/M2C carbides takes place on dislocations. The growth of these carbides proceeds by the diffusion of elements to the dislocations, which has been modeled using Dictra software, confirming the rate of the reaction as well as the depletion of carbide formers in the matrix. For longer aging times, particle coarsening will decrease the number density of particles with a transition from dislocation-based carbides to separate rounded carbides.

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Precipitation in Al-Li-Zr alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121338 ◽

1992 ◽

Vol 50 (1) ◽

pp. 186-187

Author(s):

D.M. Vanderwalker

Keyword(s):

Fracture Toughness ◽

Precipitation Hardening ◽

Weight Ratio ◽

High Strength ◽

Transmission Electron ◽

Water Quench ◽

Aluminum Lithium ◽

Aluminum Lithium Alloys ◽

Lithium Alloys ◽

Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

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Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126135 ◽

1987 ◽

Vol 45 ◽

pp. 246-247

Author(s):

R.A. Herring

Keyword(s):

Device Fabrication ◽

High Concentration ◽

Tem Analysis ◽

Defect Clusters ◽

High Fluences ◽

Small Defect ◽

Before And After ◽

The Matrix ◽

The Difference ◽

Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

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Development of Prolonged Delivery of Tramadol and Dissolution Translation by Statistical Data Treatment

International Journal of Pharmaceutical Sciences and Nanotechnology ◽

10.37285/ijpsn.2011.4.1.5 ◽

2011 ◽

Vol 4 (1) ◽

pp. 1331-1337

Author(s):

P B Parejiya ◽

B S Barot ◽

P K Shelat

Keyword(s):

Drug Release ◽

Study Data ◽

Stability Study ◽

Dissolution Time ◽

Matrix Tablet ◽

Burst Effect ◽

The Matrix ◽

The Mean ◽

The Difference ◽

Dissolution Efficiency

The present study was carried out to fabricate a prolonged design for tramadol using Kollidon SR (Polyvinyl acetate and povidone based matrix retarding polymer). Matrix tablet formulations were prepared by direct compression of Kollidon SR of a varying proportion with a fixed percentage of tramadol. Tablets containing a 1:0.5 (Drug: Kollidon SR) ratio exhibited a rapid rate of drug release with an initial burst effect. Incorporation of more Kollidon SR in the matrix tablet extended the release of drug with subsequent minimization of the burst effect as confirmed by the mean dissolution time, dissolution efficiency and f2 value. Among the formulation batches, a direct relationship was obtained between release rate and the percentage of Kollidon SR used. The formulation showed close resemblance to the commercial product Contramal and compliance with USP specification. The results were explored and explained by the difference of micromeritic characteristics of the polymers and blend of drug with excipients. Insignificant effects of various factors, e.g. pH of dissolution media, ionic strength, speed of paddle were found on the drug release from Kollidon-SR matrix. The formulation followed the Higuchi kinetic model of drug release. Stability study data indicated stable character of Batch T6 after short-term stability study.

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Precipitation hardening and recrystallization behavior of Al Mg Er Zr alloys

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2016.06.045 ◽

2016 ◽

Vol 687 ◽

pp. 143-151 ◽

Cited By ~ 23

Author(s):

S.P. Wen ◽

W. Wang ◽

W.H. Zhao ◽

X.L. Wu ◽

K.Y. Gao ◽

...

Keyword(s):

Precipitation Hardening ◽

Recrystallization Behavior ◽

Zr Alloys

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ηQ Meson Photoproduction in Ultrarelativistic Heavy Ion Collisions

Advances in High Energy Physics ◽

10.1155/2017/2379319 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Gong-Ming Yu ◽

Gao-Gao Zhao ◽

Zhen Bai ◽

Yan-Bing Cai ◽

Hai-Tao Yang ◽

...

Keyword(s):

Heavy Ion Collisions ◽

Hadron Collider ◽

Heavy Ion ◽

Relativistic Heavy Ion Collisions ◽

Heavy Quarkonium ◽

Color Singlet ◽

Initial State ◽

Color Octet ◽

Ion Collisions ◽

The Matrix

The transverse momentum distributions for inclusive ηc,b meson described by gluon-gluon interactions from photoproduction processes in relativistic heavy ion collisions are calculated. We considered the color-singlet (CS) and color-octet (CO) components within the framework of Nonrelativistic Quantum Chromodynamics (NRQCD) in the production of heavy quarkonium. The phenomenological values of the matrix elements for the color-singlet and color-octet components give the main contribution to the production of heavy quarkonium from the gluon-gluon interaction caused by the emission of additional gluon in the initial state. The numerical results indicate that the contribution of photoproduction processes cannot be negligible for midrapidity in p-p and Pb-Pb collisions at the Large Hadron Collider (LHC) energies.

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