Development of substructure in 1100 aluminum during cold rolling

1978 ◽  
Vol 36 (1) ◽  
pp. 596-597
Author(s):  
D.L. Rohr ◽  
S.S. Hecker
Keyword(s):  
Room Temperature ◽  
Mechanical Response ◽  
Large Strains ◽  
Plastic Response ◽  
Final Thickness ◽  
Commercially Pure ◽  
Thin Foils ◽  
Transmission Electron ◽  
Aluminum Plates ◽  
Comprehensive Study

The plastic response of metals at very large plastic strains is of considerable interest for practical and academic reasons. The question of the existence of a saturation stress remains largely unanswered because most experiments are not carried out to sufficiently large strains. In this paper we report our preliminary findings on the development of substructure in 1100 aluminum during rolling to reductions of 99.8%. This is part of a comprehensive study of microstructure and mechanical response of metals to large uniaxial and biaxial deformations.Commercially pure (1100) aluminum plates, annealed at 500°C, were rolled at room temperature from various starting thicknesses to a final thickness of 0.127 mm in a 2-high laboratory rolling mill. Sheets with final reductions ranging from 9.1 to 99.8% were examined by transmission electron microscopy. Thin foils were prepared directly from the 0.127-mm thick sheets by electropolishing with a 50cc-50cc-2cc HNO3-CH3OH-HCl solution in a jet polisher.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

On the disappearance of fine, disc-like features from thin foils of steel

1991 ◽  
Vol 49 ◽  
pp. 608-609
Author(s):  
S. W. Thompson
Keyword(s):  
Room Temperature ◽  
Sheet Steel ◽  
Rolled Sheet ◽  
Steel Company ◽  
Thin Foils ◽  
Transmission Electron ◽  
Fine Carbide ◽  
Iced Water ◽  
Cold Rolled ◽  
Carbide Particles

Fine carbide particles form in quenched-and-aged specimens of iron containing a small amount of carbon. Similar precipitation occurs in ferrite grains within dual-phase steels. The particles have been described as discs or loops, typically about 20 run in diameter and 2 nm thick, which lie on ﹛100﹜ planes within ferrite grains. The precipitates are believed to form in association with vacancies and produce increases in hardness and yield strength. Two studies showed that these features disappeared after heating specimens in the transmission electron microscope (TEM), and this note reports further on this phenomenon.Continuously annealed and cold-rolled sheet steel (provided by Inland Steel Company) contained (in wt pet) 0.087 C, 0.97 Mn, 0.27 Si, 0.034 Al, 0.008 S, and 0.005 N. Specimens were intercritically annealed at 770°C for five minutes and quenched in iced water. Tensile testing was conducted within one day of heat treatment, and then specimens were stored at room temperature for about six months. Thin foils were produced by conventional thinning methods and jet polished at 75 V and 80 mA in an electrolyte containing 95% acetic acid and 5% perchloric acid. Specimens were examined in a Philips EM400 operated at 120 kV.

TEM In-Situ Study of Dislocation Motion in B2 NiAl Single Crystals

1996 ◽  
Vol 460 ◽  
Author(s):  
B. Ghosh ◽  
M. A. Crimp
Keyword(s):  
Single Crystals ◽  
High Purity ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Dislocation Motion ◽  
Thermal Treatments ◽  
Commercially Pure ◽  
Transmission Electron ◽  
Uniform Manner

ABSTRACTIn an effort to understand dislocation mobility in stoichiometric NiAl single crystals, in-situ tensile deformation experiments have been performed in a transmission electron microscope. Commercially pure and high purity single crystals with <001> and <110> orientations have been examined. Two different thermal treatments were adopted in order to effect the mechanical response. Dislocation motion was observed in all samples. Pre-existing dislocations, either isolated or tangled, were not observed to move at any point leading up to sample failure. Cross-slip of the mobile dislocations was observed in some cases. In commercially pure single crystals, dislocations were found to move at a much slower rate and uniform manner in contrast to motion in high purity single crystals which occurs by rapid jumps.

Observations of the Cell Structure of Heavily Rolled Phosphor Bronze

1973 ◽  
Vol 31 ◽  
pp. 162-163
Author(s):  
R. N. Caron ◽  
S. Shapiro
Keyword(s):  
Cell Structure ◽  
Rolling Plane ◽  
Average Thickness ◽  
Rolled Sample ◽  
Final Thickness ◽  
Standard Methods ◽  
Thin Foils ◽  
Transmission Electron ◽  
Cold Rolled ◽  
Cold Worked

Transmission electron microscopy has often been used to observe the nature of the heavily cold worked condition in metals in order to evaluate the effect of this microstructure on subsequent processes and properties. However, interpretation of a heavily cold rolled microstructure when viewed normal to the rolling plane is made difficult by the fact that the average thickness of the elongated cells resulting from such deformation is often smaller than the thickness of the foil. The final thickness of a heavily rolled structure is often too thin for convenience in making thin foils trans- verse to the rolline plane. The technique of plating copper to thicken the thin cold rolled sample sufficiently for om pat ibility with standard methods for preparing transmission foils has been successfully used.

Recrystallization Behavior of Aluminum Thin Foils with Various Purity

2016 ◽  
Vol 879 ◽  
pp. 648-652
Author(s):  
Hyun Woo Lee ◽  
Seok Hong Min ◽  
Tae Kwon Ha
Keyword(s):  
Cold Rolling ◽  
High Purity ◽  
Room Temperature ◽  
Al Alloy ◽  
Recrystallization Behavior ◽  
Time Intervals ◽  
Recrystallization Kinetics ◽  
Thin Foils ◽  
Aluminum Plates ◽  
Kinetics Of

Recrystallization kinetics of aluminum with various purities from 99.5 to 99.999(5N) has been investigated in this study. Aluminum plates of 10 mm thickness with various purities were solution-treated at 400oC for 24 hrs and then rolled into sheets of 50 μm thickness at room temperature. Cold rolling was conducted on samples with various purities from 99.9 to 99.999 including commercial AA 1050 Al alloy and high purity through about 20 passes to obtain thin foils of 50 μm thickness. Accumulative rolling was employed when sample thickness reached at 1 mm and thin foils were successfully obtained for all samples. Hardness was measured just after cold rolling at room temperature as a function of time up to 1hr to elucidated recrystallization behavior. For aluminum with 99.999% purity, recrystallization occurred after 200 s and finished at 360 s. Recrystallization kinetics of aluminum at high temperatures from 100 to 350oC were investigated by measure hardness after annealing thin foils for various time intervals ranging from 1 s to 24 hrs. For high purity sample with 99.999% purity, recrystallization finished just after 1 s even at the relatively low temperature of 100oC, while recrystallization of commercial AA 1050 (2N) alloy finished after 360 s at 350oC.

A TEM Study of Bubbles Growth with Temperature in Xenon and Krypton Implanted Uranium Dioxide

2012 ◽  
Vol 323-325 ◽  
pp. 191-196 ◽  
Author(s):  
Amélie Michel ◽  
C. Sabathier ◽  
G. Carlot ◽  
M. Cabié ◽  
S. Bouffard ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Uranium Dioxide ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Number Density ◽  
Thin Foils ◽  
Transmission Electron ◽  
Growth Phenomenon ◽  
Increasing Temperature

Transmission electron microscopy (TEM) characterizations were carried out on a set of UO2 thin foils previously implanted at room temperature with 400 keV Xe2+ and 250 keV Kr2+ ions at the fluence 7.1015 at.cm-2 (equivalent to 1 at.%/at. UO2). The experiment was devoted to the study of the evolution of the fission gases bubbles populations with increasing temperature. Annealings were performed in the laboratory furnace at 600°C, 800°C, 1000°C for 12h, 1400°C for 4h and 1500°C for 2h under Ar-5%H2 atmosphere. For each annealing condition and for as-implanted specimens the bubble population has been characterized in size and number density. A comparison between Xe and Kr has been done that showed a similar behaviour. Globally, from the as-implanted sample to the 1500°C annealed, the bubbles growth phenomenon and the microstructure evolution with temperature was put in relieve.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

Phenomena Associated with Oxygen in Titanium

1967 ◽  
Vol 25 ◽  
pp. 310-311
Author(s):  
E. U. Lee ◽  
P. A. Garner ◽  
J. S. Owens
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Microstructural Changes ◽  
Electrolytic Polishing ◽  
Interstitial Impurities ◽  
Thin Foils ◽  
Transmission Electron ◽  
Iodide Titanium ◽  
Alpha Titanium

Evidence for ordering (1-6) of interstitial impurities (O and C) has been obtained in b.c.c. metals, such as niobium and tantalum. In this paper we report the atomic and microstructural changes in an oxygenated c.p.h. metal (alpha titanium) as observed by transmission electron microscopy and diffraction.Oxygen was introduced into zone-refined iodide titanium sheets of 0.005 in. thickness in an atmosphere of oxygen and argon at 650°C, homogenized at 800°C and furnace-cooled in argon. Subsequently, thin foils were prepared by electrolytic polishing and examined in a JEM-7 electron microscope, operated at 100 KV.

Scanning and Transmission Electron Microscopy of Human Red Blood Cells

1969 ◽  
Vol 27 ◽  
pp. 44-45
Author(s):  
A.J. Tousimis ◽  
T.R. Padden
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Cells ◽  
Room Temperature ◽  
Type Specimen ◽  
New Combination ◽  
Human Red Blood Cells ◽  
Transmission Electron ◽  
Microscope Slides ◽  
Scanning Electron

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

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