On mechanisms for solid state amorphizing transformations in metallic materials

1991 ◽  
Vol 24 (12) ◽  
pp. 2190-2195 ◽  
Author(s):  
I A Ovid'ko
Keyword(s):  
Solid State ◽  
Metallic Materials

scholarly journals Influence of the M and M’ Metals on the Carbides Population in As-Cast M’-based Alloys Designed to be MC-Strengthened

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Patrice Berthod
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Solid State ◽  
Ambient Temperature ◽  
Molten Glass ◽  
Turbine Blades ◽  
Metallic Materials ◽  
Cast State ◽  
Base Element ◽  
Solid State Cooling

High temperature applications such as turbine blades for aeronautics or molten glass-shaping tools require the use of refractory metallic materials. Among the later ones, cast superalloys based on some transition metals and reinforced by MC carbides stay in good place and their metallurgy merits to be well known. This work consists in a general exploration of the as-cast microstructures which can be obtained after solidification and solid state cooling down to ambient temperature for a wide series of alloys for which the base element and the MC-former element both vary. For fixed contents in chromium and carbon contents, the compositions of a total of nineteen alloys were considered. These alloys are based on Ni, Co, Fe or Nb and the M content was each time chosen to favor the appearance of TiC, TaC, NbC, HfC or ZrC, as single carbide in a given alloy. After elaboration, metallographic samples were observed by electron microscopy to investigate the obtained microstructures. The obtained results show first that the MC carbides were in many cases successfully obtained at the expense of other possible carbides (for all Co-based alloys for example) but there are also several exceptions (notably for some Ni-based alloys). Second, the obtained monocarbides have a eutectic origin and they are script-liked shaped. However they are here too some exceptions, as the rare HfC obtained in a Nb-base). In general, the results obtained in this work show that the principle of dendritic matrix combined with MC carbides with a script-like morphology is not necessarily obtained: the nature of the {base element, MC-former element} combination governs the microstructure of the alloy in its as-cast state for these particular  compositions in chromium and carbon. In some cases other carbides may appear and the microstructures may be even of another type.

Design on Transfer Piping of Molten Metallic Materials for Squeeze Casting

2013 ◽  
Vol 675 ◽  
pp. 93-97
Author(s):  
Hao Nian Min ◽  
Ming Shao ◽  
Wen Zhang
Keyword(s):  
Solid State ◽  
Molten Metal ◽  
Thermal Equilibrium ◽  
Thermal Conduction ◽  
Molten Aluminum ◽  
Squeeze Casting ◽  
Heating Power ◽  
Metallic Materials ◽  
Electromagnetic Pump ◽  
State Regulator

The spout at the connection of the pipe and the chamber is easily clogged when a large amount of molten metal is conveyed to the chamber in squeeze casting for large parts. In order to reduce the chances of clogging and clean up quickly when clogged, a quickly removable pipe is designed. The pipe is heated through thermal conduction by resistance wire, and thermal equilibrium is used to derive the power of heating element. Solid-state regulator is applied to control the heating power. Molten aluminum is conveyed from furnace to chamber using electromagnetic pump. The experiment shows that the molten metal flowing through the pipe is smooth, and the temperature of molten metal can be maintained stability.

Effects of Nano-Ceramic Particle Addition for Cold Sprayed Fluoropolymer Coatings

2019 ◽  
Vol 813 ◽  
pp. 141-146 ◽  
Author(s):  
W. Lock Sulen ◽  
Kesavan Ravi ◽  
Chrystelle Bernard ◽  
Nicolas Mary ◽  
Yuji Ichikawa ◽  
...  
Keyword(s):  
Solid State ◽  
Traverse Speed ◽  
Deposition Efficiency ◽  
Ceramic Particle ◽  
Metallic Materials ◽  
Gas Temperature ◽  
Deposition Technique ◽  
Crystalline Polymers ◽  
Modification Technique ◽  
Particle Addition

Semi-crystalline polymers such as fluoropolymers are extremely difficult to coat with using solid-state deposition technique such as cold spray (CS) due to its high viscoelastic-viscoplastic behavior. Generally, fluoropolymers solid-state deposition using CS are characterized by a relatively low deposition efficiency (DE) as compared to metallic materials using this deposition technique. In this article, the study on the effect of hydrophobic fumed nanosilica (FNS) and fumed nanoalumina (FNA) in Perfluoroalkoxy (PFA) solid-state deposition using CS has been studied. This study incorporated certain parameters related to the CS process. In addition, powder modification technique using hydrophobic FNS and FNA as additive to feedstock has been studied as well. The results show a number of parameters affected the DE; particle size, traverse speed, gas temperature, and addition of hydrophobic fumed nanoparticles, indicated a better DE. Moreover, PFA coating produced in this manner, retained its hydrophobicity.

Preparation of Thin Cadmium Telluride Samples for Electron Microscope Studies

1974 ◽  
Vol 32 ◽  
pp. 548-549
Author(s):  
T. J. Magee ◽  
J. Peng ◽  
J. Bean
Keyword(s):  
Electron Microscope ◽  
Sulfuric Acid ◽  
Solid State ◽  
Sample Preparation ◽  
Cadmium Telluride ◽  
Potassium Dichromate ◽  
Optical Components ◽  
The Past ◽  
Solid State Devices

Cadmium telluride has become increasingly important in a number of technological applications, particularly in the area of laser-optical components and solid state devices, Microstructural characterizations of the material have in the past been somewhat limited because of the lack of suitable sample preparation and thinning techniques. Utilizing a modified jet thinning apparatus and a potassium dichromate-sulfuric acid thinning solution, a procedure has now been developed for obtaining thin contamination-free samples for TEM examination.

The Collagenic Molecular Structural Unit of Solid State Complexes

1971 ◽  
Vol 29 ◽  
pp. 478-479
Author(s):  
Kenneth M. Richter ◽  
John A. Schilling
Keyword(s):  
Molecular Weight ◽  
Solid State ◽  
Structural Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naoh Treatment

The structural unit of solid state collagen complexes has been reported by Porter and Vanamee via EM and by Cowan, North and Randall via x-ray diffraction to be an ellipsoidal unit of 210-270 A. length by 50-100 A. diameter. It subsequently was independently demonstrated by us in dog tendon, dermis, and induced complexes. Its detailed morphologic, dimensional and molecular weight (MW) aspects have now been determined. It is pear-shaped in long profile with m diameters of 57 and 108 A. and m length of 263 A. (Fig. 1, tendon, KMnO4 fixation, Na-tungstate; Fig. 2a, schematic of unit in long, C, and x-sectional profiles of its thin, xB, and bulbous, xA portions; Fig. 2b, tendon essentially unmodified by ether and 0.4 N NaOH treatment, Na-tungstate). The unit consists of a uniquely coild cable, c, of ṁ 22.9 A. diameter and length of 2580-3316 A. The cable consists of three 2nd-strands, s, each of m 10.6 A.

SEM Examination of a Used Diamond Knife

1971 ◽  
Vol 29 ◽  
pp. 452-453
Author(s):  
J. Temple Black
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
High Magnification ◽  
Metallic Materials ◽  
Wide Spread ◽  
Thin Sections ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron ◽  
Diamond Knife

Since its introduction by Fernandez-Moran, the diamond knife has gained wide spread usage as a common material for cutting of thin sections of biological and metallic materials into thin films for examination in the transmission electron microscope. With the development of high voltage E.M. and scanning transmission E.M., microtomy applications will become increasingly important in the preparation of specimens. For those who can afford it, the diamond knife will thus continue to be an important tool to accomplish this effort until a cheaper but equally strong and sharp tool is found to replace the diamond, glass not withstanding.In Figs. 1 thru 3, a first attempt was made to examine the edge of a used (β=45°) diamond knife by means of the scanning electron microscope. Because diamond is conductive, first examination was tried without any coating of the diamond. However, the contamination at the edge caused severe charging during imaging. Next, a thin layer of carbon was deposited but charging was still extensive at high magnification - high voltage settings. Finally, the knife was given a light coating of gold-palladium which eliminated the charging and allowed high magnification micrographs to be made with reasonable resolution.

Observation of secondary slip systems in tungsten bicrystals

1984 ◽  
Vol 42 ◽  
pp. 478-479
Author(s):  
J. R. Fekete ◽  
R. Gibala
Keyword(s):  
Stress Field ◽  
Grain Boundaries ◽  
Deformation Behavior ◽  
Stress Axis ◽  
Polycrystalline Materials ◽  
Slip Systems ◽  
Metallic Materials ◽  
Twist Boundary ◽  
Secondary Slip ◽  
Plane Normal

The deformation behavior of metallic materials is modified by the presence of grain boundaries. When polycrystalline materials are deformed, additional stresses over and above those externally imposed on the material are induced. These stresses result from the constraint of the grain boundaries on the deformation of incompatible grains. This incompatibility can be elastic or plastic in nature. One of the mechanisms by which these stresses can be relieved is the activation of secondary slip systems. Secondary slip systems have been shown to relieve elastic and plastic compatibility stresses. The deformation of tungsten bicrystals is interesting, due to the elastic isotropy of the material, which implies that the entire compatibility stress field will exist due to plastic incompatibility. The work described here shows TEM observations of the activation of secondary slip in tungsten bicrystals with a [110] twist boundary oriented with the plane normal parallel to the stress axis.

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