A Study on Morphologies of Second Phases in the Mg-Sr and Mg-Sr-Y Alloys

2010 ◽  
Vol 146-147 ◽  
pp. 336-339
Author(s):  
Jing Gao ◽  
Hai Cheng Yu ◽  
Fang Fang Zhao ◽  
Ming Hu
Keyword(s):  
Aspect Ratio ◽  
Reduction Method ◽  
Mg Alloy ◽  
Heat Resistant ◽  
Second Phases ◽  
Micro Structures

In this paper, the author successfully fabricated Mg-Sr and Mg-Sr-Y alloys by melting-leaching reduction method using SF6 and N2 as protected gas. The micro-structures of the alloys were investigated in details，and the results showed that dendrite α-Mg and eutectic α-Mg and Mg17Sr2 were the main phases in the Mg-Sr alloy, while Mg -Sr-Y alloys were composed of dendrite α-Mg and small eutectic α-Mg and Mg17Sr2 and tiny Mg24Y5. More eutectics were distributed around dendrite crystals in the Mg-Sr alloy, the Mg17Sr2 with aspect ratio of 6 : 1 were aligned and discontinuous lamellae, a Mg17Sr2 was irregular particles. The microstructures of Mg-Sr-Y alloy refined, Mg17Sr2 and tiny Mg24Y5 particles with size of 2-3μm distributed in the α-Mg dendrites and boundaries. The fomation and growth of both Mg24Y5 and Mg17Sr2 in the alloys were stated. It is obvious that the role of improving the heat-resistant Mg alloy of Mg24Y5 is more than Mg17Sr2.

The Special Role of Anodic Second Phases in the Micro-galvanic Corrosion of EW75 Mg Alloy

2016 ◽  
Vol 189 ◽  
pp. 190-195 ◽  
Author(s):  
Jinhui Liu ◽  
Yingwei Song ◽  
Jiachen Chen ◽  
Peng Chen ◽  
Dayong Shan ◽  
...  
Keyword(s):  
Galvanic Corrosion ◽  
Mg Alloy ◽  
Special Role ◽  
Second Phases

Investigation into the role of poly(vinylpyrrolidone) in the growth of high aspect ratio silver nanowires

2021 ◽  
Vol 128 ◽  
pp. 108558
Author(s):  
Yuyue Guo ◽  
Yangfei Hu ◽  
Xiaojiong Luo ◽  
Shudong Lin ◽  
Jiwen Hu ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Silver Nanowires

Flow Measurements in a Nozzle Guide Vane Passage With a Low Aspect Ratio and Endwall Contouring

2000 ◽  
Author(s):  
Steven W. Burd ◽  
Terrence W. Simon
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Guide Vane ◽  
Flow Measurements ◽  
Vast Number ◽  
Aspect Ratios ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

The vast number of turbine cascade studies in the literature has been performed in straight-endwall, high-aspect-ratio, linear cascades. As a result, there has been little appreciation for the role of, and added complexity imposed by, reduced aspect ratios. There also has been little documentation of endwall profiling at these reduced spans. To examine the role of these factors on cascade hydrodynamics, a large-scale nozzle guide vane simulator was constructed at the Heat Transfer Laboratory of the University of Minnesota. This cascade is comprised of three airfoils between one contoured and one flat endwall. The geometries of the airfoils and endwalls, as well as the experimental conditions in the simulator, are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow field in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indicate that the acceleration imposed by endwall contouring and airfoil turning is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significantly from that adjacent to the straight endwall.

scholarly journals Role of growth rate on the orientational alignment of Escherichia coli in a slit

2017 ◽  
Vol 4 (6) ◽  
pp. 170463 ◽  
Author(s):  
Julian Sheats ◽  
Bianca Sclavi ◽  
Marco Cosentino Lagomarsino ◽  
Pietro Cicuta ◽  
Kevin D. Dorfman
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Aspect Ratio ◽  
Density Fluctuations ◽  
Global Alignment ◽  
Similar Amount ◽  
Cell Area ◽  
Nematic Ordering ◽  
Side Walls

We present experimental data on the nematic alignment of Escherichia coli bacteria confined in a slit, with an emphasis on the effect of growth rate and corresponding changes in cell aspect ratio. Global alignment with the channel walls arises from the combination of local nematic ordering of nearby cells, induced by cell division and the elongated shape of the cells, and the preferential orientation of cells proximate to the side walls of the slit. Decreasing the growth rate leads to a decrease in alignment with the walls, which is attributed primarily to effects of changing cell aspect ratio rather than changes in the variance in cell area. Decreasing confinement also reduces the degree of alignment by a similar amount as a decrease in the growth rate, but the distribution of the degree of alignment differs. The onset of alignment with the channel walls is coincident with the slits reaching their steady-state occupancy and connected to the re-orientation of locally aligned regions with respect to the walls during density fluctuations.

Assessment of surface energetic heterogeneity of synthetic Na- saponites. The role of layer charge

Clay Minerals ◽  
2002 ◽  
Vol 37 (1) ◽  
pp. 39-57 ◽  
Author(s):  
L. J. Michot ◽  
F. Villiéras
Keyword(s):  
Aspect Ratio ◽  
Gas Adsorption ◽  
High Energy ◽  
Layer Charge ◽  
Adsorption Mechanisms ◽  
Energetic Heterogeneity ◽  
Complex Adsorption ◽  
Adsorption Energy Distribution ◽  
Synthetic Saponite

AbstractHigh-resolution gas adsorption techniques were used to analyse the evolution of the aspect ratio and adsorption energy distribution on synthetic saponite samples with increasing layer charge. Using Ar as a gaseous probe, the aspect ratio of the saponite particles can be determined easily by decomposing the derivative adsorption isotherms and taking into account high-energy sites which can be assigned to talc-like ditrigonal cavities. Changes in the shape of the elementary particles are observed for layer charges above 1.30, i.e. when all the ditrigonal cavities contain at least one Al atom substituting for Si. When N2 is used as a probe, high-energy sites that could be wrongly interpreted as micropores on the basis of classical t-plot treatments are observed whatever the layer charge. Using the information obtained from both Ar and N2, schemes for describing adsorption can be proposed for all layer charges and suggest complex adsorption mechanisms for charged clay minerals.

Physical and Electrochemical Evidence for the Role of a Mg Hydride Species in Mg Alloy Corrosion

CORROSION ◽  
10.5006/2918 ◽  
2019 ◽  
Vol 75 (1) ◽  
pp. 58-68 ◽  
Author(s):  
W. Jeffrey Binns ◽  
Fareshta Zargarzadah ◽  
Vahid Dehnavi ◽  
Jian Chen ◽  
James J. Noël ◽  
...  
Keyword(s):  
Mg Alloy
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