Transformation Crystallography and Plasticity of the δ→α′ Transformation in Plutonium Alloys

2003 ◽  
Vol 802 ◽  
Author(s):  
C. R. Krenn ◽  
M. A. Wall ◽  
A. J. Schwartz
Keyword(s):  
Habit Plane ◽  
Room Temperature ◽  
Face Centered Cubic ◽  
Thermally Activated ◽  
Delta Phase ◽  
Transmission Electron ◽  
Δ Phase ◽  
Face Centered ◽  
Prime Phase

ABSTRACTIn delta phase Pu-Ga alloys, the transformation from the ductile face-centered cubic (fcc) δ phase that is retained at room temperature to the brittle low-temperature monoclinic alpha-prime phase is a thermally activated diffusionless transformation with double-c kinetics. Accurate modeling of the phase transformation requires detailed understanding of the role of plastic flow during the transformation and of the crystallographic transformation path. Using transmission electron microscopy (TEM), we find a significant increase in dislocation density in δ near the α′ plates, which suggests that plastic deformation contributes to the accommodation of the 20% reduction in volume during the transformation. Analysis of a series of optical micrographs of partially transformed alloys suggests that the α′ habit plane is usually nearly perpendicular to <111> δ. However, a small number of TEM observations support a habit plane near <112> or <123>, in agreement with earlier work.

Synthesis of NiCu Alloy Nanoparticles by Arc Plasma Evaporation

2013 ◽  
Vol 710 ◽  
pp. 157-160
Author(s):  
Li Xin Li ◽  
Zhong Juan Yang ◽  
Ming Li
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Average Crystallite Size ◽  
Alloy Nanoparticles ◽  
Face Centered Cubic ◽  
Arc Plasma ◽  
Transmission Electron ◽  
Face Centered ◽  
Bulk Alloys ◽  
Microscopy Images

The NiCu nanoparticles were synthesized from NixCu1-x (20 at. % < x < 80 at. %) bulk alloys with arc plasma technique. The experimental results indicated that the crystal structure of the powders is face centered cubic structure, the same as the bulk raw materials. The composition between the prepared powders and the bulk alloys altered with the content of the nickel and copper. With Scherrer equation, the average crystallite size was determined to be 50 nm, which is consistent with the results achieved from the TEM (transmission electron microscopy) images. Also the TEM images showed that some of the nanoparticles could aggregate and grew into micro-size particles at room temperature. The largest size of the grown particle at room temperature was about 1 μm.

W/O Microemulsion Preparation of ZnSe Nanometer Materials Characterization

2012 ◽  
Vol 472-475 ◽  
pp. 1967-1970
Author(s):  
Cui Zhi Dong ◽  
Li Fang Zhang ◽  
Zhi Min Cui ◽  
Ming Xi Zhang ◽  
Qing Jun Zhang
Keyword(s):  
Aging Time ◽  
Room Temperature ◽  
Materials Characterization ◽  
Microemulsion System ◽  
Face Centered Cubic ◽  
Cubic Crystal ◽  
Nanometer Materials ◽  
Transmission Electron ◽  
The Face ◽  
Face Centered

ZnSe is important Ⅱ-Ⅵ semiconductor luminescence materials, and it is the structure of sphalerite and is the face-centered cubic crystal. W/O microemulsion method has the peculiarity of tester simpleness, easy manipulation, room temperature react etc. In this paper ZnSe nanometer line was synthesized in CTAB/cyclohexane/isobutanol/water quatemary microemulsion system. The morphology of the final products were characterized by transmission electron microscopy. according to the means, this paper researches the effect of aging time and the reactant contentration to nanometer materials. The result is that the nanometer line can be obtained through the different reactant concentration and the aging time under certain conditions. Finally, according to TEM chart, this paper infers the formation mechanism of the ZnSe.

Effects of Hydrogen on Diffusion Bonding of TiAl-Based Intermetallics with Hydrogenated Ti6AI4V Alloy Interlayer Containing 0.5wt% Hydrogen

2013 ◽  
Vol 750-752 ◽  
pp. 624-629
Author(s):  
Lei Jia ◽  
Long Fan
Keyword(s):  
Diffusion Bonding ◽  
Room Temperature ◽  
Hexagonal Structure ◽  
Martensite Phase ◽  
Ti6al4v Alloy ◽  
Face Centered Cubic ◽  
Bonding Parameters ◽  
Δ Phase ◽  
Temperature Shear ◽  
Face Centered

The direct diffusion bonding of TiAl-based intermetallics and the diffusion bonding of TiAl-based intermetallics with hydrogenated Ti6Al4V alloys interlayer containing 0.5wt% hydrogen were carried out. The effects of hydrogen on diffusion bonding were investigated by SEM, EPMA, XRD, TEM and TG/DSC. The good joint was formed at 850°C for 15 min under a pressure of 15MPa at the diffusion bonding of TiAl-based intermetallics with hydrogenated Ti6Al4V alloy interlayer containing 0.5wt% hydrogen, and the room temperature shear strength was up to 290MPa. Relatived to direct diffusion bonding of TiAl-based intermetallic, the bonding parameters decreased prodigiously. According to the experimental observations, the Ti6Al4V alloy hydrogenated 0.5 wt% consisted of close-packed hexagonal structure α′ martensite phase, face-centered cubic structure of δ-phase, α and βH structure. The lamellar δ hydride and βH phase disappeared after bonding, and the lamellar (α+β) structure were formed. Because of the dehydrogenation during bonding, metastable hydride containing low hydrogen appeared. The remaining hydrogen in Ti6Al4V alloy at high temperatures enhanced the capacity of the plastic deformation and the diffusion ability of the alloy elements, which helped to improve the spread of the atom.

Faceted antiphase boundaries in GaAs grown on Ge

1987 ◽  
Vol 45 ◽  
pp. 314-315
Author(s):  
N.-H. Cho ◽  
S. McKernan ◽  
C.B. Carter ◽  
K. Wagner
Keyword(s):  
Cross Section ◽  
Atomic Resolution ◽  
Face Centered Cubic ◽  
Electrical Behavior ◽  
Sphalerite Structure ◽  
Antiphase Boundaries ◽  
Transmission Electron ◽  
Face Centered ◽  
Quality Material ◽  
Simulated Images

Interest has recently increased in the possibility of growing III-V compounds epitactically on non-polar substrates to produce device quality material. Antiphase boundaries (APBs) may then develop in the GaAs epilayer because it has sphalerite structure (face-centered cubic with a two-atom basis). This planar defect may then influence the electrical behavior of the GaAs epilayer. The orientation of APBs and their propagation into GaAs epilayers have been investigated experimentally using both flat-on and cross-section transmission electron microscope techniques. APBs parallel to (110) plane have been viewed at the atomic resolution and compared to simulated images.Antiphase boundaries were observed in GaAs epilayers grown on (001) Ge substrates. In the image shown in Fig.1, which was obtained from a flat-on sample, the (110) APB planes can be seen end-on; the faceted APB is visible because of the stacking fault-like fringes arising from a lattice translation at this interface.

Microstructure Characterization of Ag Nanoparticles Prepared by Hydrothermal Method

2012 ◽  
Vol 476-478 ◽  
pp. 1138-1141
Author(s):  
Zhi Qiang Wei ◽  
Qiang Wei ◽  
Li Gang Liu ◽  
Hua Yang ◽  
Xiao Juan Wu
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Hydrothermal Method ◽  
Ag Nanoparticles ◽  
Average Particle Size ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Face Centered

Ag nanoparticles were successfully synthesized by hydrothermal method under the polyol system combined with traces of sodium chloride, Silver nitrate(AgNO3) and polyvinylpyrrolidone (PVP) acted as the silver source and dispersant respectively. The samples by this process were characterized via X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED) to determine the chemical composition, particle size, crystal structure and morphology. The experiment results indicate that the crystal structure of the samples is face centered cubic (FCC) structure as same as the bulk materials, The specific surface area is 24 m2/g, the particle size distribution ranging from10 to 50 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results.

scholarly journals In-Situ TEM Annealing Observation of Helium Bubble Evolution in Pre-Irradiated FeCoNiCrTi0.2 Alloys

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3727
Author(s):  
Huanhuan He ◽  
Zhiwei Lin ◽  
Shengming Jiang ◽  
Xiaotian Hu ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Vacuum Arc ◽  
In Situ Tem ◽  
Face Centered Cubic ◽  
Helium Bubble ◽  
High Entropy ◽  
Helium Bubbles ◽  
Transmission Electron ◽  
Bubble Evolution ◽  
Face Centered

The FeCoNiCrTi0.2 high-entropy alloys fabricated by vacuum arc melting method, and the annealed pristine material, are face centered cubic structures with coherent γ’ precipitation. Samples were irradiated with 50 keV He+ ions to a fluence of 2 × 1016 ions/cm2 at 723 K, and an in situ annealing experiment was carried out to monitor the evolution of helium bubbles during heating to 823 and 923 K. The pristine structure of FeCoNiCrTi0.2 samples and the evolution of helium bubbles during in situ annealing were both characterized by transmission electron microscopy. The annealing temperature and annealing time affect the process of helium bubbles evolution and formation. Meanwhile, the grain boundaries act as sinks to accumulate helium bubbles. However, the precipitation phase seems have few effects on the helium bubble evolution, which may be due to the coherent interface and same structure of γ’ precipitation and matrix.

scholarly journals The Examination of Calcium ion Implanted Alumina with Energy Filtered Transmission Electron Microscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 413-414
Author(s):  
E.M. Hunt ◽  
J.M. Hampikian ◽  
N.D. Evans
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pure Aluminum ◽  
Lattice Parameter ◽  
Face Centered Cubic ◽  
Ion Channeling ◽  
Transmission Electron ◽  
Knoop Microhardness ◽  
Aluminum Nanocrystals ◽  
Face Centered

Ion implantation can be used to alter the optical response of insulators through the formation of embedded nano-sized particles. Single crystal alumina has been implanted at ambient temperature with 50 keV Ca+ to a fluence of 5 x 1016 ions/cm2. Ion channeling, Knoop microhardness measurements, and transmission electron microscopy (TEM) indicate that the alumina surface layer was amorphized by the implant. TEM also revealed nano-sized crystals ≈7 - 8 nm in diameter as seen in Figure 1. These nanocrystals are randomly oriented, and exhibit a face-centered cubic structure (FCC) with a lattice parameter of 0.409 nm ± 0.002 nm. The similarity between this crystallography and that of pure aluminum (which is FCC with a lattice parameter of 0.404 nm) suggests that they are metallic aluminum nanocrystals with a slightly dilated lattice parameter, possibly due to the incorporation of a small amount of calcium.Energy-filtered transmission electron microscopy (EFTEM) provides an avenue by which to confirm the metallic nature of the aluminum involved in the nanocrystals.

Strengthening Evaluation in a Composite Mg-RE Alloy Using TEM

2011 ◽  
Vol 678 ◽  
pp. 75-84 ◽  
Author(s):  
Marcello Cabibbo
Keyword(s):  
Electron Microscopy ◽  
Metal Matrix ◽  
Room Temperature ◽  
Strengthening Mechanism ◽  
Composite Alloy ◽  
Specific Strength ◽  
High Specific Strength ◽  
Transmission Electron ◽  
Sic Ceramic

Magnesium alloys containing rare earth elements are known to have high specific strength and corrosion resistance. The addition of SiC ceramic particles makes the metal matrix composite stronger with better wear and creep resistance and a still good machinability. The role of the reinforcement particles to the enhanced strength can be quantitatively evaluated using transmission electron microscopy (TEM). This paper presents a quantitative strengthening evaluation in a SiC Mg-RE composite alloy. The different contributions were determined by TEM inspections. The microstructure strengthening mechanism was studied after room temperature compression specimens. The way of combining the different contributions and the comparison to the measured yield stress, is also discussed and justified.

scholarly journals In Situ Synthesis of Polyaniline Based Ceramic Wastes Composites: Dielectric and Electrical Properties

2021 ◽  
Author(s):  
M. Sohail ◽  
Adnan Shahzad ◽  
Mian Gul Sayed ◽  
Ihsan Ullah ◽  
M. Omer ◽  
...  
Keyword(s):  
Composite Material ◽  
High Frequency ◽  
Room Temperature ◽  
In Situ Synthesis ◽  
Face Centered Cubic ◽  
Dielectric Analysis ◽  
Photovoltaic Detectors ◽  
Pani Composite ◽  
Face Centered

Abstract In the present study, ceramic wastes collected from the premises of industrial zone in Peshawar, KP Pakistan were investigated. An effort has been made to recycle and use the ceramic wastes as fillers in polymeric composites. The negative cost ceramic wastes were purified and activated thermally. The elemental composition and pellets of the wastes were investigated through SEM/EDX analysis. Waste/Polyaniline (PANI) composite was synthesized via in-situ free radical polymerization technique. SEM of the composites showed the uniform distribution of fillers particles in the PANI matrix. XRD studies confirmed that the prepared composite material had a face- centered cubic geometry with distinct preferential orientations. Dielectric analysis showed that the materials exhibit active performance at high frequency regions (3MHz to 3GHz) at room temperature. The results show decrease in dielectric losses and capacitance (1.6 pF) at high frequency regions. AC conductivity of the composite has been increased up to 37.95 Scm-1. This revealed the effect of PANI on the ceramic wastes while increasing its conductance performance. This suggests that the composite material can be investigated for use in photovoltaic detectors, electro-responsive capacitors and power applications.

scholarly journals Dynamic transition of current-driven single-skyrmion motion in a room-temperature chiral-lattice magnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Licong Peng ◽  
Kosuke Karube ◽  
Yasujiro Taguchi ◽  
Naoto Nagaosa ◽  
Yoshinori Tokura ◽  
...  
Keyword(s):  
Electric Current ◽  
Motion Tracking ◽  
Room Temperature ◽  
Dynamic Transition ◽  
Spintronic Devices ◽  
Transmission Electron ◽  
Flow Motion ◽  
Lorentz Transmission Electron Microscopy ◽  
And Control

AbstractDriving and controlling single-skyrmion motion promises skyrmion-based spintronic applications. Recently progress has been made in moving skyrmionic bubbles in thin-film heterostructures and low-temperature chiral skyrmions in the FeGe helimagnet by electric current. Here, we report the motion tracking and control of a single skyrmion at room temperature in the chiral-lattice magnet Co9Zn9Mn2 using nanosecond current pulses. We have directly observed that the skyrmion Hall motion reverses its direction upon the reversal of skyrmion topological number using Lorentz transmission electron microscopy. Systematic measurements of the single-skyrmion trace as a function of electric current reveal a dynamic transition from the static pinned state to the linear flow motion via a creep event, in agreement with the theoretical prediction. We have clarified the role of skyrmion pinning and evaluated the intrinsic skyrmion Hall angle and the skyrmion velocity in the course of the dynamic transition. Our results pave a way to skyrmion applications in spintronic devices.

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