Experimental characterization and modeling of metallic materials with hexagonal closed-packed structure

Author(s):  
Oana Cazacu ◽  
Benoit Revil-Baudard
2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Daisuke Matsuura ◽  
Kun'ichi Miyazawa ◽  
Tokushi Kizuka

We synthesized cobalt- (Co-) doped C60 nanowhiskers (NWs) by applying a liquid-liquid interfacial precipitation method using a C60-saturated toluene solution and 2-propanol with Co nitrate hexahydrate (Co(NO3)3⋅6H2O). Heating the NWs at 873–1173 K produced carbon nanocapsules (CNCs) that encapsulated Co clusters with a hexagonal-closed-packed structure. After heating at 1273 K, the encapsulated Co clusters in CNCs were transformed into orthorhombic Co2C clusters. It was found that Co- and Co2C-encapsulated CNCs can be produced by varying heating temperature.


Author(s):  
Róbert Bidulský ◽  
Federico Simone Gobber ◽  
Alessandro Fais ◽  
Jana Bidulská ◽  
Marco Actis Grande

In this study one of the most innovative sintering techniques up to date was evaluated: Electro-Sinter-Forging (ESF). Despite it has been proved to be effective in densifying several different metallic materials and composites, bearing steels such as 100Cr6 have never been processed so far. Pre-alloyed Astaloy CrM powders have been ad-mixed with either graphite or graphene and then processed by ESF to produce a 100Cr6 equivalent composition. Porosity has been evaluated by optical microscopy and compared to that one of 100Cr6 commercial samples. Mechanical properties such as hardness and transverse rupture strength were tested on samples produced by employing different process parameters and then submitted to different treatments (machining, heat treatment). The experimental characterization highlighted that porosity is the factor mostly affecting mechanical resistance of the samples, correlating linearly to the transverse rupture strength. Hardness on the other side does not correlate to the mechanical resistance because process related cracking has a higher effect on the final properties. Promising results were obtained that give room to the sinterability by ESF of materials difficult to sinter by conventional press and sinter techniques.


2007 ◽  
Vol 539-543 ◽  
pp. 1707-1712 ◽  
Author(s):  
Suk Bong Kang ◽  
Hyoung Wook Kim ◽  
Sang Su Jeong ◽  
Jae Woon Kim

Magnesium alloys have been known as the best lightweight metallic materials for various applications of electronic equipments and automobile parts due to high specific strength and stiffness. The needs for wrought magnesium alloys have been increased for the application to structural parts in the form of sheets and bars. However, magnesium has a hexagonal closed-packed (HCP) crystal structure with a limited number of operative slip systems at room temperature, and its formability is restricted to mild deformation. The improvement of the formability of magnesium sheets for real applications is important. In order to increase formability of magnesium sheets at elevated temperature, one promising way is a grain refinement.


RSC Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 2353-2358
Author(s):  
Ye Yuan ◽  
Yue-Wen Fang ◽  
Yi-Feng Zhao ◽  
Chun-Gang Duan

We combine the piezoelectric wurtzite ZnO and the ferroelectric (111) BaTiO3 as a hexagonal closed-packed structure and report a systematic study on the ferroelectric behavior induced by the interface and the transport properties between electrodes.


Author(s):  
J. Temple Black

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.


Author(s):  
J. R. Fekete ◽  
R. Gibala

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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