Microcrystalline Materials and Microstructure Refining

Author(s):  
Oscar A. Kaibyshev
1993 ◽  
Vol 321 ◽  
Author(s):  
K. C. Wang ◽  
B. Y. Chen ◽  
K. C. Hsu ◽  
T. R. Yew ◽  
H. L. Hwang

ABSTRACTMicrocrystalline silicon films were deposited by diluted-hydrogen method and hydrogen-atom-treatment method at 250°C in a plasma enhanced chemical vapor deposition system and they were characterized by nuclear magnetic resonance, Raman spectroscopy, and optical bandgap Measurements. One-Mask a-Si:H thin film transistors (TFT's) were fabricated with those microcrystalline materials as the channel layer. The highest electron mobilities of the TFT's fabricated by diluted-hydrogen method and hydrogen-atom-treatment method were 1.23 and 1.04 cm2/V•s, respectively without any thermal treatment steps.


2011 ◽  
Vol 21 ◽  
pp. s242-s246 ◽  
Author(s):  
Xin WANG ◽  
Wen-zhen CHEN ◽  
Lian-xi HU ◽  
Guo-jun WANG ◽  
Er-de WANG

2013 ◽  
Vol 570 ◽  
pp. 80-84 ◽  
Author(s):  
George C. Papavassiliou ◽  
Georgia Pagona ◽  
George A. Mousdis ◽  
Nikolaos Karousis

1988 ◽  
Vol 132 ◽  
Author(s):  
Frans Spaepen

ABSTRACTHistorically, non-periodic models have usually found preference over microcrystalline ones for describing the structure of amorphous materials. Nevertheless, truly microcrystalline materials do exist, and the characteristic, monotonically decreasing isothermal calorimetric signal associated with the growth of the grains, can sometimes be used to identify them unambiguously. An example of the identification of the micro-quasicrystalline structure of some sputtered aluminum-transition metal alloys is discussed.


2014 ◽  
Vol 61 (4) ◽  
pp. 539-552
Author(s):  
Marek Stanisław Weglowski

Abstract The article presents the effect of rotational and travelling speed and down force on the spindle torque acting on the tool in Friction Stir Processing (FSP) process. The response surface methodology (RSM) was applied to find a dependence combining the spindle torque acting on the tool with the rotational speed, travelling speed and the down force. The linear and quadratic models with interaction between parameters were used. A better fitting was achieved for a quadratic model. The studies have shown that the increase in rotational speed causes a decrease in the torque while the increase in travelling speed and down force causes an increase in the torque. The tests were conducted on casting aluminium alloy AlSi9Mg. Metallography examination has revealed that the application of FSP process results in a decrease in the porosity in the modified material and microstructure refining in the stir zone. The segregation of Si and Fe elements was evident in the parent material, while in the friction stir processed area this distribution was significantly uniform.


2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
J. A. Montemayor-Aldrete ◽  
R. Mendez-Olvera ◽  
P. Ugalde-Velez ◽  
G. Torres-Villaseñor ◽  
M. del Castillo-Mussot

A local measurement technique for the study of the kinetic processes of emerging of grains or blocks of grains from the inner volume to the free surface of superplastic materials during deformation is presented and used for the case of the Cd-Zn eutectic alloy deformed at room temperature. This technique could be used to evaluate the approximate time of fracture due to fissure or cavitation growth in samples under superplastic deformation. In principle, this technique will be useful for the development of physical procedures, which allows retarding the process of formation of low mismatch angle, , between neighboring grains, process which gives place to blocks of grains which dynamically behave as units under the shear stress action. For materials with nanocrystalline structures, such processes are expected to be higher than those of the case of microcrystalline materials.


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