Laser Pulse Melting of Metals: Epitaxy and Allotropy

1980 ◽  
Vol 1 ◽  
Author(s):  
L. Buene ◽  
E. N. Kaufmann ◽  
C. M. Preece ◽  
C. W. Draper
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Layer ◽  
High Temperature ◽  
Laser Pulse ◽  
Single Crystals ◽  
Laser Power ◽  
Rutherford Backscattering ◽  
Scanning Electron ◽  
Crystallographic Orientations

ABSTRACTLaser pulse melted single crystals of several metals have been examined by the Rutherford backscattering/channeling technique and with optical and scanning electron microscopy. Metals belonging to the three major structure groups; fcc (Ni, Pd, Rh); bcc(Mo, Nb, W, Fe); and hcp (Be, Ti, Re) have been studied at various laser power levels and in different crystallographic orientations. Of these cases, Be, Ti and Fe show high temperature allotropes which are expected to influence the character of the resolidified surface layer.

Imaging of polymer single crystals in low-voltage, high-resolution scanning electron microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 1106-1107
Author(s):  
W.W. Adams ◽  
G. Price ◽  
A. Krause
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Single Crystals ◽  
Low Voltage ◽  
Polymer Surface ◽  
Beam Current ◽  
Image Features ◽  
First Results ◽  
Scanning Electron

It has been shown that there are numerous advantages in imaging both coated and uncoated polymers in scanning electron microscopy (SEM) at low voltages (LV) from 0.5 to 2.0 keV compared to imaging at conventional voltages of 10 to 20 keV. The disadvantages of LVSEM of degraded resolution and decreased beam current have been overcome with the new generation of field emission gun SEMs. In imaging metal coated polymers in LVSEM beam damage is reduced, contrast is improved, and charging from irregularly shaped features (which may be unevenly coated) is reduced or eliminated. Imaging uncoated polymers in LVSEM allows direct observation of the surface with little or no charging and with no alterations of surface features from the metal coating process required for higher voltage imaging. This is particularly important for high resolution (HR) studies of polymers where it is desired to image features 1 to 10 nm in size. Metal sputter coating techniques produce a 10 - 20 nm film that has its own texture which can obscure topographical features of the original polymer surface. In examining thin, uncoated insulating samples on a conducting substrate at low voltages the effect of sample-beam interactions on image formation and resolution will differ significantly from the effect at higher accelerating voltages. We discuss here sample-beam interactions in single crystals on conducting substrates at low voltages and also present the first results on HRSEM of single crystal morphologies which show some of these effects.

Features of Wear of Abrasive Grains Depending on Microcuttings Speed of Steels

2016 ◽  
Vol 674 ◽  
pp. 189-194 ◽  
Author(s):  
Margarita A. Skotnikova ◽  
Galina V. Tsvetkova ◽  
Nikolay A. Krylov ◽  
Evgeniy K. Ivanov ◽  
Viktoriy V. Medvedeva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Layer ◽  
Thin Surface Layer ◽  
Abrasive Grains ◽  
Microscopy Method ◽  
Scanning Electron Microscopy Method ◽  
Electron Microscopy Method ◽  
Scanning Electron ◽  
Alloy Titanium

In this article by the example of two abrasive materials from oxide of aluminum and nitride of boron, the processes developing in a thin surface layer between a grain of abrasive and the material, processed by microcutting with speeds of 40 and 160 m/s, the preforms from armko-iron, steels R18, 45, H18N10T and alloy titanium VT6 are investigated, using the scanning electron microscopy method.

scholarly journals Effect of Different Cooling Regimes on the Mechanical Properties of Cementitious Composites Subjected to High Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Jiangtao Yu ◽  
Wenfang Weng ◽  
Kequan Yu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
High Temperature ◽  
Significant Influence ◽  
Microstructural Characterization ◽  
Cementitious Composite ◽  
Engineered Cementitious Composite ◽  
Before And After ◽  
Scanning Electron

The influence of different cooling regimes (quenching in water and cooling in air) on the residual mechanical properties of engineered cementitious composite (ECC) subjected to high temperature up to 800°C was discussed in this paper. The ECC specimens are exposed to 100, 200, 400, 600, and 800°C with the unheated specimens for reference. Different cooling regimens had a significant influence on the mechanical properties of postfire ECC specimens. The microstructural characterization was examined before and after exposure to fire deterioration by using scanning electron microscopy (SEM). Results from the microtest well explained the mechanical properties variation of postfire specimens.

A Porous TiO2 Coating with Vermiform Morphology Formed on Ti through Micro-Arc Oxidation

2013 ◽  
Vol 652-654 ◽  
pp. 1818-1821
Author(s):  
Zhen Fei Liu ◽  
Wei Qiang Wang ◽  
Min Qi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Temperature ◽  
Rutile Phase ◽  
Sodium Tetraborate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Porous Titania ◽  
Micro Arc Oxidation ◽  
Scanning Electron

A porous titania (TiO2) coating with vermiform slots was prepared on the Ti substrate through micro-arc oxidation (MAO) treatment using sodium tetraborate as electrolyte. Morphologies and phase structure were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Results show that the rutile phase increases and anatase decreases gradually with increasing MAO time. The electrolyte of sodium tetraborate has significant influence on the formation of vermiform coatings, which determine the corrosive patterning in the first stage during MAO processing. The evolution of vermiform morphology is proposed as followed: some corrosive pores appear on the surface before arcing; afterward, the adjacent micropores in the dense regions link each other due to the high temperature result from continuous arc action; then, the micropores grow up to big pits and combine with each other with increasing MAO treating time; finally, the vermiform morphology forms on the surface of Ti metal.

Oxidation Resistance and Insulation of AlPO4/Al2O3 Coating on Tungsten Substrate at High Temperature

2017 ◽  
Vol 1142 ◽  
pp. 168-172
Author(s):  
Ai Ling Fan ◽  
Ying Kun Xue ◽  
Wei Tian Li
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Temperature ◽  
Composite Coating ◽  
Oxidation Resistance ◽  
Electronic Device ◽  
Sol Gel ◽  
Gel Method ◽  
Scanning Electron ◽  
Tungsten Substrate

To improve the oxidation resistance and insulation of tungsten electronic device at high temperature, an AlPO4/Al2O3 composite coating was synthesized on the tungsten substrate by sol-gel method. The morphology of coating was investigated by scanning electron microscopy (SEM). Compared to the blank specimens, the coated ones exhibit excellent oxidation resistance and insulation at about 1100, which can be attributed to the compact coating without porosity and crack. Up to 1200, the effects of coating became dramatically poor. The electron conductivity mechanism was discussed.

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