EM study of phase transformation in zinc coatings

1992 ◽  
Vol 50 (1) ◽  
pp. 66-67
Author(s):  
C. A. Drewien
Keyword(s):  
Automotive Industry ◽  
Galvanic Corrosion ◽  
Zinc Alloy ◽  
Operating Voltage ◽  
Automotive Body ◽  
In Situ Heating ◽  
Equilibrium Phases ◽  
Zinc Coatings ◽  
Thermal Stability Of

Electrodeposited iron-zinc alloy (EZA) coatings, used for barrier and galvanic corrosion protection of steel by the automotive industry, are deposited under conditions, which give rise to small grain sizes and non-equilibrium phases. Subsequent processing of automotive body panels requires a paint bake cycle of 175 °C for 30 minutes. The as-deposited microstructure has not been investigated by TEM due to difficulty of sample preparation, and information on the effect of heat treatment upon EZA coatings is lacking. In this study, the as-deposited microstructure of a 6 w/o Fe EZA coating is investigated with electron microscopy, and in-situ heating in the TEM is used to observe the thermal stability of the microstructure.A 6 w/o bulk iron content EZA coating was electrodeposited from a chloride bath onto a steel surface. The 7 μm thick coating was removed from the substrate, and three mm disks, punched from the material, were electropolished at 30-40 V in a room temperature, aqueous chromic-acetic acid mix. Samples were imaged with a JEOL 6300 FEG-SEM operated with an accelerating voltage of 1 keV and with a Philips 430 EM under an operating voltage of 250 keV.

scholarly journals Thermal stability of helium bubble superlattice in Mo under TEM in-situ heating

2018 ◽  
Vol 505 ◽  
pp. 207-211 ◽  
Author(s):  
Jian Gan ◽  
Cheng Sun ◽  
Lingfeng He ◽  
Yongfeng Zhang ◽  
Chao Jiang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Helium Bubble ◽  
In Situ Heating ◽  
Thermal Stability Of

scholarly journals Phase Formation and Thermal Stability of Reactively Sputtered YTaO4–ZrO2 Coatings

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 692
Author(s):  
Bastian Stelzer ◽  
Katrin Pingen ◽  
Marcus Hans ◽  
Damian M. Holzapfel ◽  
Silvia Richter ◽  
...  
Keyword(s):  
Phase Region ◽  
X Ray Diffraction ◽  
Al2o3 Substrate ◽  
Grain Sizes ◽  
Phase Pure ◽  
In Situ Heating ◽  
Α Al2o3 ◽  
T Phase ◽  
Thermal Stability Of

Y(1−x)/2Ta(1−x)/2ZrxO2 coatings with 0 to 44 mol% ZrO2 were synthesized by sputtering. Phase-pure M’-YTaO4 coatings were obtained at a substrate temperature of 900 °C. Alloying with ZrO2 resulted in the growth of M’ along with t-Zr(Y,Ta)O2 for ≤15 mol%, while for ≥28 mol%, ZrO2 X-ray diffraction (XRD) phase-pure metastable t was formed, which may be caused by small grain sizes and/or kinetic limitations. The former phase region transformed into M’ and M and the latter to an M’ + t and M + t phase region upon annealing to 1300 and 1650 °C, respectively. In addition to M and t, T-YTa(Zr)O4 phase fractions were observed at room temperature for ZrO2 contents ≥28 mol% after annealing to 1650 °C. T phase fractions increased during in situ heating XRD at 80 °C. At 1650 °C, a reaction with the α-Al2O3 substrate resulted in the formation of AlTaO4 and an Al-Ta-Y-O compound.

scholarly journals Structural Core-Shell beyond Chemical Homogeneity in Non-Stoichiometric Cu5FeS4 Nano-Icosahedrons: An in Situ Heating TEM Study

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 4 ◽  
Author(s):  
Bin Zhang ◽  
Xiaowei Zhao ◽  
Tianrui Dong ◽  
Aijuan Zhang ◽  
Xiao Zhang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Stability ◽  
Core Shell ◽  
Practical Applications ◽  
The Core ◽  
Shell Nanostructures ◽  
In Situ Heating ◽  
Intrinsic Strain ◽  
Thermal Stability Of

Thermal stability of core-shell structured nanoparticles is of vital importance to their practical applications at elevated temperature. Understanding the evolution of chemical distribution and the crystal structure of core-shell nanostructures with temperature variation at the nanoscale will open the route for practical applications and property enhancement of nanoparticles through proper design of new nanomaterials. In this study, core-shell non-stoichiometric Cu5FeS4 icosahedral nanoparticles were investigated by in situ heating transmission electron microscopy. Compared to the high structural and compositional stability at room temperature, the interdiffusion of Cu and Fe atoms became significant, ending up with disappearance of chemical difference in the core and shell over 300 °C. In contrast, different crystal structures of the core and shell were preserved even after heating at 350 °C, indicating the high structural stability. The inconsistency between chemical composition and crystal structure should be ascribed to the interaction between the intrinsic strain existing in the icosahedrons and various structures of this material system. In other words, the geometrically intrinsic strain of the nano-icosahedrons is helpful to modulate/maintain the core-shell structure. These findings open new opportunities for revealing the thermal stability of core-shell nanostructures for various applications and are helpful for the controllable design of new core-shell nanostructures.

Thermal stability of self-assembled ordered three-phase Au–BaTiO3–ZnO nanocomposite thin films via in situ heating in TEM

Nanoscale ◽  
2020 ◽  
Vol 12 (46) ◽  
pp. 23673-23681
Author(s):  
Shikhar Misra ◽  
Di Zhang ◽  
Ping Lu ◽  
Haiyan Wang
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Ex Situ ◽  
Three Phase ◽  
Nanocomposite Thin Films ◽  
Vertically Aligned ◽  
In Situ Heating ◽  
Self Assembled ◽  
Thermal Stability Of

Thermal stability of an ordered three-phase Au–BaTiO3–ZnO vertically aligned nanostructure by both ex situ annealing under air and vacuum conditions, and in situ heating in TEM in vacuum has been demonstrated.

Thermal stability of C-F/C-F2 bonds in fluorinated graphene detected by in-situ heating infrared spectroscopy

2021 ◽  
Author(s):  
Yulong Li ◽  
Jingliang Cheng ◽  
Xu Wang ◽  
Yang Liu ◽  
Xiangyang Liu
Keyword(s):  
Thermal Stability ◽  
Infrared Spectroscopy ◽  
In Situ Heating ◽  
Fluorinated Graphene ◽  
Thermal Stability Of

Thermal stability of fluorinated graphene (FG) plays an important role in its application and research, so it is necessary to conduct in-depth research on thermal stability of C-F bond in...

In situ HREM Study on the Thermal Stability of Atomic Layer Epitaxy Grown InAs/GaAs Quantum Dots

2004 ◽  
Vol 839 ◽  
Author(s):  
H. S. Kim ◽  
J. H. Suh ◽  
C. G. Park ◽  
S. J. Lee ◽  
S. K. Noh ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Quantum Dots ◽  
Early Stage ◽  
Atomic Layer ◽  
High Resolution Electron Microscopy ◽  
Atomic Layer Epitaxy ◽  
Average Height ◽  
In Situ Heating ◽  
Thermal Stability Of

ABSTRACTSelf-assembled InAs/GaAs quantum dots (QDs) were grown by the atomic layer epitaxy technique and the structure and the thermal stability of QDs have been studied by using high resolution electron microscopy with in-situ heating experiment capability. The QDs were found to form a hemispherical structure with {136} side facet in the early stage of growth. The average height and diameter of the QD were found to be ∼ 5.5 nm and ∼ 23 nm, respectively. Upon capping by GaAs layer, however, the apex structure of QD changed to a flat one. In-situ heating experiment within TEM revealed that the uncapped QD remained stable until 580°C. However, at temperature above 600°C, the QD structure became flat due to the fast decrease of QD height. After flattening, the atoms diffused from the InAs QD to the GaAs substrate, resulting in the total collapse. The density of the QD decreased abruptly by this collapse and most QDs disappeared at above 600°C.

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

Innovative Closed-Cell Reactor Permits In Situ Heating and Gas Reactions with Atomic Resolution at Atmospheric Pressure

2012 ◽  
Vol 18 (S2) ◽  
pp. 1118-1119 ◽  
Author(s):  
L. Allard ◽  
S.H. Overbury ◽  
M.B. Katz ◽  
W.C. Bigelow ◽  
D. Nackashi ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Atomic Resolution ◽  
Closed Cell ◽  
Cell Reactor ◽  
In Situ Heating ◽  
Gas Reactions

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

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