Sequential laser pulse thermal excitation method for the detection of defects in metallic materials

2021 ◽  
Author(s):  
Wei Fang ◽  
Xue Yang ◽  
Xangyu Wang ◽  
Gangbo Hu ◽  
Ning Tao ◽  
...  
2019 ◽  
Vol 19 (24) ◽  
pp. 11891-11899 ◽  
Author(s):  
Xiaoqing Yang ◽  
Junlong Chen ◽  
Piqiang Su ◽  
Xuexue Lei ◽  
Jing Lei ◽  
...  

2020 ◽  
Author(s):  
Changrui Liao ◽  
Tianhang Yang ◽  
Jinli Han

Abstract Fiber Bragg grating has been successfully fabricated in the silica microfiber by the use of femtosecond laser point-by-point inscription. Temporal thermal response of the fabricated silica microfiber Bragg grating has been measured by the use of the CO2 laser thermal excitation method, and the result shows that the time constant of the microfiber Bragg grating is reduced by an order of magnitude compared with the traditional single-mode fiber Bragg grating and the measured time constant is ~ 21ms.


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.


2000 ◽  
Vol 10 (PR9) ◽  
pp. Pr9-641-Pr9-646
Author(s):  
P. Chevrier ◽  
J. R. Klepaczko
Keyword(s):  

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