The Effect of Thermal Treatment on the Microstructural Evolution of an Al-Cu Alloy

2003 ◽  
Author(s):  
Tracie L. Zoeller ◽  
Thomas H. Sanders
Keyword(s):  
Aluminum Alloy ◽  
Chemical Composition ◽  
Marked Effect ◽  
Volume Fraction ◽  
Solidification Rate ◽  
Thermal Treatments ◽  
Large Volume Fraction ◽  
Cu Alloy ◽  
Processing Step ◽  
Alloy Microstructure

Following solidification, an aluminum alloy microstructure is highly segregated. The microstructure consists of cored dendrites with various soluble and insoluble phases present in the dendritic regions. The solidification rate has a marked effect on the amount of coring that an alloy experiences. Understanding the effects of the solidification rate is important in explaining differences in microstructures. Subsequent heat treatments are performed to homogenize the microstructure. The microstructure evolution after each processing step is dependent upon the previous microstructures. The variation in local chemical composition may promote or hinder precipitation of new phases. A large volume fraction of coarse insoluble phases can lead to the occurrence of recrystallized grains via particle stimulated nucleation, while inhomogeneous solute distribution can lead to the precipitation of an uneven distribution of dispersoid phases. The effect of solidification rate and subsequent thermal treatments on the microstructure of an Al-4Cu alloy will be investigated and experimental and numerical results will be presented.

The rate of solidification and the effects of local composition on the subsequent nucleation of Al2Cu2Mn3 dispersoid phase in Al-4Cu-0.3Fe-0.4Mn-0.2Si alloys

2004 ◽  
Vol 120 ◽  
pp. 61-68
Author(s):  
T. L. Zoeller ◽  
T. H. Sanders
Keyword(s):  
Aluminum Alloy ◽  
Phase Particle ◽  
Solidification Rate ◽  
Copper Alloys ◽  
Grain Morphology ◽  
Second Phase ◽  
Thermal Treatments ◽  
Local Composition ◽  
Aluminum Copper Alloys ◽  
Alloy Microstructure

Following solidification, an aluminum alloy microstructure is highly segregated. The microstructure consists of cored dendrites with various soluble and insoluble phases present in the inter-dendritic regions. The solidification rate has a marked effect on the amount of coring as well as grain dimensions and second phase particle size and spacing. Post-solidification cooling rates as well as subsequent heat treatments also affect the evolution of the microstructure. Understanding the effects of these thermal treatments is important in explaining differences in microstructures that are observed in alloys of identical compositions. The focus of this study is to determine the interaction between the coring of copper across dendrites during solidification and the precipitation of dispersoids during the homogenization treatments of an alloy. An aluminum alloy whose composition is in the range of Al-4Cu-0.3Fe-0.4Mn-0.2Si is ideally suited for this study for several reasons. First it is similar to a host of commercial aluminum copper alloys, and the presence of Mn, Fe, and Si affect the distribution of particles that control grain morphology in these alloys. Preliminary experimental results are discussed. Current numerical analysis techniques will be examined and possible methods to treat the problem will be presented.

Optimization of the Chemical Composition and Homogenization Treatment of AA7020 Aluminum Alloy

2010 ◽  
Vol 89-91 ◽  
pp. 177-183 ◽  
Author(s):  
Ali Reza Eivani ◽  
H. Ahmed ◽  
Jie Zhou ◽  
Jurek Duczczyk
Keyword(s):  
Aluminum Alloy ◽  
Chemical Composition ◽  
Strain Rate ◽  
Hot Deformation ◽  
Volume Fraction ◽  
Hot Compression ◽  
Compression Tests ◽  
Homogenization Treatment ◽  
Aa7020 Aluminum Alloy

Four variants of AA7020 aluminum alloy having different Zr and Cr contents were investigated aiming at reaching high recrystallization resistance during and after hot deformation. Isothermal homogenization treatments were performed at temperatures of 390-550 °C for 2 to 48 hours. The uni-axial hot compression tests were conducted at 450 °C and strain rate of 10 s-1 at a strain of 0.6. Thereafter, the samples were annealed at 550 °C for 10 min. It was found that the samples with the highest Zr and Cr contents showed the lowest volume fraction of recrystallized grains which was attributed to the highest volume fraction of Zr- and Cr-containing dispersoids formed during homogenization. The optimum homogenization treatment to achieve highest recrystallization resistance for these samples was 470 °C for 24 hours.

Thermomechanical Treatment of a 4340 Ni-Cr-Mo Alloy Steel

1981 ◽  
Vol 39 ◽  
pp. 314-315 ◽  
Author(s):  
M.T. Jahn ◽  
J.C. Yang ◽  
C.M. Wan
Keyword(s):  
Mechanical Property ◽  
Chemical Composition ◽  
Alloy Steel ◽  
Thermomechanical Treatment ◽  
Room Temperature ◽  
Good Combination ◽  
Thermal Treatments ◽  
Low Carbon ◽  
4340 Steel ◽  
Good Improvement

4340 Ni-Cr-Mo alloy steel is widely used due to its good combination of strength and toughness. The mechanical property of 4340 steel can be improved by various thermal treatments. The influence of thermomechanical treatment (TMT) has been studied in a low carbon Ni-Cr-Mo steel having chemical composition closed to 4340 steel. TMT of 4340 steel is rarely examined up to now. In this study we obtain good improvement on the mechanical property of 4340 steel by TMT. The mechanism is explained in terms of TEM microstructures4340 (0.39C-1.81Ni-0.93Cr-0.26Mo) steel was austenitized at 950°C for 30 minutes. The TMTed specimen (T) was obtained by forging the specimen continuously as the temperature of the specimen was decreasing from 950°C to 600°C followed by oil quenching to room temperature. The thickness reduction ratio by forging is 40%. The conventional specimen (C) was obtained by quenching the specimen directly into room temperature oil after austenitized at 950°C for 30 minutes. All quenched specimens (T and C) were then tempered at 450, 500, 550, 600 or 650°C for four hours respectively.

Study on Over-Burnt Temperature and Heat Treatment of a New Al-Mg-Si-Cu Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 1516-1519
Author(s):  
Yi Meng ◽  
Zhi Hao Zhao ◽  
Jian Zhong Cui
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloy ◽  
Homogenization Temperature ◽  
Microstructure Analysis ◽  
Cu Alloy ◽  
Homogenization Time ◽  
The Way

The over-burnt temperature of a new Al-Mg-Si-Cu Aluminum alloy was studied by means of DSC and microstructure analysis, as a result of the homogenization temperature being obtained. A favorable homogenization time was got by the way of the dependence of area fractions of remnant phases on homogenization time being calculated. According to experimentation results, the over-burnt temperature of the new Al-Mg-Si-Cu Aluminum alloy was 570°C, and the way to homogenize the new alloy at 560°C for 24h was excellemt.

The Role of Nuclear Stiffness and Resilience in Mechanotransduction

2010 ◽  
Author(s):  
Kris Noel Dahl ◽  
Elizabeth A. Booth-Gauthier ◽  
Alexandre J. S. Ribeiro ◽  
Zhixia Zhong
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Live Cell Imaging ◽  
Volume Fraction ◽  
Direct Role ◽  
Intact Cells ◽  
Large Volume Fraction ◽  
Nuclear Mechanics ◽  
Model Cell

Mechanical force is found to be increasingly important during development and for proper homeostatic maintenance of cells and tissues. The nucleus occupies a large volume fraction of the cell and is interconnected with the cytoskeleton. Here, to determine the direct role of the nucleus itself in converting forces to changes in gene expression, also known as, mechanotransduction, we examine changes in nuclear mechanics and gene reorganization associated with cell fate and with extracellular force. We measure mechanics of nuclei in many model cell systems using micropipette aspiration to show changes in nuclear mechanics. In intact cells we characterize the rheological changes induced in the genome organization with live cell imaging and particle tracking, and we suggest how these changes relate to gene expression.

scholarly journals Increasing of the Mechanical Properties of Friction Stir Welded Joints of 6061 Aluminum Alloy by Introducing Alumina Particles

2017 ◽  
Vol 17 (2) ◽  
pp. 29-40 ◽  
Author(s):  
M. A. Tashkandi ◽  
J. A. Al-Jarrah ◽  
M. Ibrahim
Keyword(s):  
Aluminum Alloy ◽  
Base Metal ◽  
Welded Joints ◽  
Volume Fraction ◽  
Welding Process ◽  
Welding Zone ◽  
6061 Aluminum Alloy ◽  
Friction Stir ◽  
Alumina Particles ◽  
Welding Line

AbstractThe main aim of this investigation is to produce a welding joint of higher strength than that of base metals. Composite welded joints were produced by friction stir welding process. 6061 aluminum alloy was used as a base metal and alumina particles added to welding zone to form metal matrix composites. The volume fraction of alumina particles incorporated in this study were 2, 4, 6, 8 and 10 vol% were added on both sides of welding line. Also, the alumina particles were pre-mixed with magnesium particles prior being added to the welding zone. Magnesium particles were used to enhance the bonding between the alumina particles and the matrix of 6061 aluminum alloy. Friction stir welded joints containing alumina particles were successfully obtained and it was observed that the strength of these joints was better than that of base metal. Experimental results showed that incorporating volume fraction of alumina particles up to 6 vol% into the welding zone led to higher strength of the composite welded joints as compared to plain welded joints.

Uniformity of Grain Coarsening in Submicron Grained Al-Sc Alloy Containing Local Variations in Texture

2005 ◽  
Vol 495-497 ◽  
pp. 609-614
Author(s):  
Michael Ferry
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Fine Particles ◽  
Volume Fraction ◽  
Marked Change ◽  
Grain Coarsening ◽  
Large Volume Fraction ◽  
Orientation Gradient ◽  
Distribution Boundary

The effect of fine particles on the uniformity of grain coarsening in a submicron grained Al-Sc alloy containing significant local variations in texture has been investigated using high resolution EBSD. The alloy was processed by severe plastic deformation and low temperature ageing to generate a fine-grained (0.8 µm diameter) microstructure containing either a dispersion of nanosized Al3Sc particles or a particle-free matrix. The initial processing generated a uniform grain size distribution, but the distribution of grain orientations was inhomogeneous with the microstructure containing colonies of grains consisting predominantly of either HAGBs or LAGBs with the latter possessing orientation gradients of up to 10 o/µm. Despite the marked differences in boundary character between these regions, the alloy undergoes slow and uniform grain coarsening during annealing at temperatures up to 500 oC with no marked change in the grain size distribution, boundary distribution and texture. A model of grain coarsening that takes into account the influence of fine particles on the kinetics of grain growth within an orientation gradient is outlined. The model predicts that a large volume fraction of fine particles (large f/r-value) tends to homogenize the overall rate of grain coarsening despite the presence of orientation gradients in the microstructure.

Shape Memory Characteristics and Superelasticity of Ti-Ni-Cu Alloy Ribbons with Nano Ti2Ni Particles

2008 ◽  
Vol 8 (2) ◽  
pp. 722-727 ◽  
Author(s):  
Tae-hyun Nam ◽  
Cheol-am Yu ◽  
Jung-min Nam ◽  
Hyun-gon Kim ◽  
Yeon-wook Kim
Keyword(s):  
Melt Spinning ◽  
Volume Fraction ◽  
Deformation Behaviour ◽  
Parent Phase ◽  
Tensile Tests ◽  
Constant Load ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Average Size ◽  
Memory Characteristics

Microstructures and deformation behaviour of Ti-45Ni-5Cu and Ti-46Ni-5Cu alloy ribbons prepared by melt spinning were investigated by transmission electron microscopy, thermal cycling tests under constant load and tensile tests. Spherical Ti2Ni particles coherent with the B2 parent phase were observed in the alloy ribbons when the melt spinning temperature was higher than 1773 K. Average size of Ti2Ni particles in the ribbons obtained at 1873 K was 8 nm, which was smaller than that (10 nm) in the ribbons obtained at 1773 K. Volume fraction of Ti2Ni phase in the ribbons obtained at 1873 K was 40%, which was larger than that (20%) in the ribbons obtained at 1773 K. The stress required at temperatures of Af + 10 K for the stress-induced martensitic transformation increased from 93 MPa to 229 MPa and apparent elastic modulus of the B2 parent phase increased from 56 GPa to 250 GPa with increasing the melt spinning temperature from 1673 K to 1873 K in Ti-45Ni-5Cu alloy ribbons. The critical stress for slip deformation of the ribbons increased by coherent Ti2Ni particles, and thus residual elongation did not occur even at 160 MPa, while considerable plastic deformation occurred at 60 MPa in the ribbons without Ti2Ni particles. Almost perfect superelastic recovery was found in the ribbons with coherent Ti2Ni particles, while only partial superelastic recovery was observed in the ribbons without coherent Ti2Ni particles.

scholarly journals Solidification Process and Volume Fraction in Sn-Ag-Cu Alloy

2010 ◽  
Vol 13 (7) ◽  
pp. 521-530 ◽  
Author(s):  
Yoshiko Takamatsu ◽  
Hisao Esaka ◽  
Kei Shinozuka
Keyword(s):  
Volume Fraction ◽  
Solidification Process ◽  
Cu Alloy

scholarly journals CCN activity of organic aerosols observed downwind of urban emissions during CARES

2013 ◽  
Vol 13 (4) ◽  
pp. 9355-9399 ◽  
Author(s):  
F. Mei ◽  
A. Setyan ◽  
Q. Zhang ◽  
J. Wang
Keyword(s):  
Chemical Composition ◽  
Water Solubility ◽  
Volume Fraction ◽  
Field Studies ◽  
High Water ◽  
Carbonaceous Aerosols ◽  
Mass Spectral ◽  
Least Squares Fit ◽  
The Relationship ◽  
Aerosol Chemical Composition

Abstract. During the Carbonaceous Aerosols and Radiative Effects Study (CARES), activation fraction of size-resolved aerosol particles and aerosol chemical composition were characterized at the T1 site (~60 km downwind of Sacramento, California) from 10 June to 28 June 2010. The hygroscopicity of CCN-active particles (κCCN) with diameter from 100 to 171 nm, derived from the size-resolved activated fraction, varied from 0.10 to 0.21, with an average of 0.15, which was substantially lower than that proposed for continental sites in earlier studies. The low κCCN value was due to the high organic volume fraction, averaged over 80% at the T1 site. The derived κCCN exhibited little diurnal variation, consistent with the relatively constant organic volume fraction observed. At any time, over 90% of the size selected particles with diameter between 100 and 171 nm were CCN active, suggesting most particles within this size range were aged background particles. Due to the large organic volume fraction, organic hygroscopicity (κorg) strongly impacted particle hygroscopicity and therefore calculated CCN concentration. For vast majority of the cases, an increase of κorg from 0.03 to 0.18, which are within the typical range, doubled the calculated CCN concentration. Organic hygroscopicity was derived from κCCN and aerosol chemical composition, and its variations with the fraction of total organic mass spectral signal at m/z 44 (f44) and O : C were compared to results from previous studies. Overall, the relationships between κorg and f44 are quite consistent for organic aerosol (OA) observed during field studies and those formed in smog chamber. Compared to the relationship between κorg and f44, the relationship between κorg and O : C exhibits more significant differences among different studies, suggesting κorg may be better parameterized using f44. A least squares fit yielded κorg = 2.04 (± 0.07) × f44 − 0.11 (± 0.01) with the Pearson R2 value of 0.71. One possible explanation for the stronger correlation between κorg and f44 is that the m/z 44 signal (mostly contributed by the CO2+ ion) is more closely related to organic acids, which may dominate the overall κorg due to their relatively high water solubility and hygroscopicity.

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