scholarly journals Symbiotic, low-temperature, and scalable synthesis of bi-magnetic complex oxide nanocomposites

2020 ◽  
Vol 2 (2) ◽  
pp. 851-859 ◽  
Author(s):  
F. Sayed ◽  
G. Kotnana ◽  
G. Muscas ◽  
F. Locardi ◽  
A. Comite ◽  
...  

Low-temperature, symbiotic synthesis of nanocomposites, with heat of formation of phase1 crystallizing phase2, and phase2 preventing grain growth of phase1.

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1004 ◽  
Author(s):  
Xianguang Zhang ◽  
Kiyotaka Matsuura ◽  
Munekazu Ohno

The occurrence of abnormal grain growth (AGG) of austenite during annealing is a serious problem in steels with carbide and/or nitride particles, which should be avoided from a viewpoint of mechanical properties. The effects of cold deformation prior to annealing on the occurrence of AGG have been investigated. It was found that the temperature range of the occurrence of AGG is shifted toward a low temperature region by cold deformation, and that the shift increases with the increase of the reduction ratio. The lowered AGG occurrence temperature is attributed to the fine and near-equilibrium AlN particles that are precipitated in the cold-deformed steel, which is readily dissolved during annealing. In contrast, coarse and non-equilibrium AlN particles precipitated in the undeformed steel, which is resistant to dissolution during annealing.


1994 ◽  
pp. 81-84
Author(s):  
Dunzhuo Dong ◽  
Kenji Murakami ◽  
Shoji Kaneko ◽  
Maoren Xiong

RSC Advances ◽  
2018 ◽  
Vol 8 (35) ◽  
pp. 19610-19615 ◽  
Author(s):  
Cheng-Ming Hsieh ◽  
Yung-Sheng Liao ◽  
Yan-Ru Lin ◽  
Chih-Ping Chen ◽  
Cheng-Min Tsai ◽  
...  

We demonstrated that urea can be used as an efficient additive for perovskite solar cells with a remarkable performance of 18.8%.


Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1344
Author(s):  
Alberto Meza ◽  
Eric Macía ◽  
Andrea García-Junceda ◽  
Luis Antonio Díaz ◽  
Paul Chekhonin ◽  
...  

In this work, new oxide dispersion strengthened (ODS) ferritic steels have been produced by powder metallurgy using an alternative processing route and characterized afterwards by comparing them with a base ODS steel with Y2O3 and Ti additions. Different alloying elements like boron (B), which is known as an inhibitor of grain growth obtained by pinning grain boundaries, and complex oxide compounds (Y-Ti-Zr-O) have been introduced to the 14Cr prealloyed powder by using mechanical alloying (MA) and were further consolidated by spark employing plasma sintering (SPS). Techniques such as x-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to study the obtained microstructures. Micro-tensile tests and microhardness measurements were carried out at room temperature to analyze the mechanical properties of the differently developed microstructures, which was considered to result in a better strength in the ODS steels containing the complex oxide Y-Ti-Zr-O. In addition, small punch (SP) tests were performed to evaluate the response of the material under high temperatures conditions, under which promising mechanical properties were attained by the materials containing Y-Ti-Zr-O (14Al-X-ODS and 14Al-X-ODS-B) in comparison with the other commercial steel, GETMAT. The differences in mechanical strength can be attributed to the precipitate’s density, nature, size, and to the density of dislocations in each ODS steel.


2007 ◽  
Vol 266 ◽  
pp. 13-28 ◽  
Author(s):  
Alan F. Jankowski

Thermal anneal treatments are used to identify the temperature range of the two dominant diffusion mechanisms – bulk and grain boundary. To assess the transition between mechanisms, the low temperature range for bulk diffusion is established utilizing the decay of static concentration waves in composition-modulated nanolaminates. These multilayered structures are synthesized using vapor deposition methods as thermal evaporation and magnetron sputtering. However, at low temperature the kinetics of grain-boundary diffusion are much faster than bulk diffusion. The synthesis of Au-Cu alloys (0-20 wt.% Cu) with grain sizes as small as 5 nm is accomplished using pulsed electro-deposition. Since the nanocrystalline grain structure is thermally unstable, these structures are ideal for measuring the kinetics of grain boundary diffusion as measured by coarsening of grain size with low temperature anneal treatments. A transition in the dominant mechanism for grain growth from grain boundary to bulk diffusion is found with an increase in temperature. The activation energy for bulk diffusion is found to be 1.8 eV·atom-1 whereas that for grain growth at low temperatures is only 0.2 eV·atom-1. The temperature for transitioning from the dominant mechanism of grain boundary to bulk diffusion is found to be 57% of the alloy melt temperature and is dependent on composition.


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