Physicochemical Aspects of the K2ZrF6 Process Allowing the Spontaneous Infiltration of SiC (or C) Preforms by Liquid Aluminium

1989 ◽  
pp. 157-163 ◽  
Author(s):  
S. Schamm ◽  
J. P. Rocher ◽  
R. Naslain
Keyword(s):  
Liquid Aluminium ◽  
Spontaneous Infiltration

scholarly journals The intimate relationship between structural relaxation and the energy landscape of monatomic liquid metals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Franz Demmel ◽  
Louis Hennet ◽  
Noel Jakse
Keyword(s):  
High Temperature ◽  
Velocity Field ◽  
Liquid State ◽  
Liquid Metals ◽  
Energy Landscape ◽  
Experimental Studies ◽  
Transport Parameter ◽  
Arrhenius Behavior ◽  
Liquid Aluminium ◽  
Potential Energy Landscape

AbstractThe characteristic property of a liquid, discriminating it from a solid, is its fluidity, which can be expressed by a velocity field. The reaction of the velocity field on forces is enshrined in the transport parameter viscosity. In contrast, a solid reacts to forces elastically through a displacement field, the particles are trapped in their potential minimum. The flow in a liquid needs enough thermal energy to overcome the changing potential barriers, which is supported through a continuous rearrangement of surrounding particles. Cooling a liquid will decrease the fluidity of a particle and the mobility of the neighbouring particles, resulting in an increase of the viscosity until the system comes to an arrest. This process with a concomitant slowing down of collective particle rearrangements might already start deep inside the liquid state. The idea of the potential energy landscape provides an attractive picture for these dramatic changes. However, despite the appealing idea there is a scarcity of quantitative assessments, in particular, when it comes to experimental studies. Here we present results on a monatomic liquid metal through a combination of ab initio molecular dynamics, neutron spectroscopy and inelastic x-ray scattering. We investigated the collective dynamics of liquid aluminium to reveal the changes in dynamics when the high temperature liquid is cooled towards solidification. The results demonstrate the main signatures of the energy landscape picture, a reduction in the internal atomic structural energy, a transition to a stretched relaxation process and a deviation from the high-temperature Arrhenius behavior of the relaxation time. All changes occur in the same temperature range at about $$1.4 \cdot T_{melting}$$ 1.4 · T melting , which can be regarded as the temperature when the liquid aluminium enters the landscape influenced phase and enters a more viscous liquid state towards solidification. The similarity in dynamics with other monatomic liquid metals suggests a universal dynamic crossover above the melting point.

Wettability of preoxidised TiAl substrates by liquid aluminium, copper, and silver

2001 ◽  
Vol 17 (10) ◽  
pp. 1293-1298 ◽  
Author(s):  
Y. Shen ◽  
W.F. Gale ◽  
J.W. Fergus ◽  
X. Wen
Keyword(s):  
Liquid Aluminium ◽  
Aluminium Copper

The interaction of liquid aluminium with silicon carbide and nitride-based ceramics

1993 ◽  
Vol 12 (4) ◽  
pp. 209-211 ◽  
Author(s):  
S. A. M. Foister ◽  
M. W. Johnston ◽  
J. A. Little
Keyword(s):  
Silicon Carbide ◽  
Liquid Aluminium

Investigation Techniques of In Situ AlMg/AlN Metal Matrix Composites via Reactive Gas Injection

2013 ◽  
Vol 837 ◽  
pp. 283-289 ◽  
Author(s):  
Raluca Maria Florea ◽  
Oana Bălţătescu ◽  
Aurelian Buzăianu ◽  
Ioan Carcea
Keyword(s):  
Metal Matrix ◽  
Gas Flow ◽  
Sem Analysis ◽  
Critical Parameters ◽  
Matrix Composites ◽  
Uniform Dispersion ◽  
Liquid Systems ◽  
Spontaneous Infiltration ◽  
Reactive Gas

In this paper characteristics of an AlMg/AlN composite produced in-situ and processed in a flowing N2 atmosphere is investigated. Some critical parameters such as the manufacturing process temperature, the percentage of the magnesium consumed, the flowing reactive gas flow and the time for completing the manufacturing are considered as variables for the parametric investigation. Moreover, the effect of different amount of Mg employed has been also investigated, since Mg acts as a catalyst at the surface both for the gas/liquid and solid/liquid systems. Traditional methods were used for the basic characterization of the composite. The microstructure of the composite was investigated by optical and scanning electron microscopy (OM, SEM). SEM analysis was performed in order to observe the microstructural evolution as a function of the Mg content and to identify some reasons of the presence of porosity or any irregularities within the metal matrix. The evolution of mechanical properties, in terms of microhardness, at different percentage of Mg were monitored. By EDS technique the distribution of the elements was obtained. Furthermore, employing an optimization process, uniform dispersion of the strengthening (AlN) particles in the metal matrix with homogeneous properties along the composite material is obtained. Based on the aforementioned statements, it can be concluded that the reactions between Al, Mg and the N2 atmosphere induce spontaneous infiltration in the metal matrix. The complete mix of properties and experimentally assessed parameters can be used for industrial purpose manufacturing design and development.

scholarly journals Reoxidation Processes Prediction in Gating System by Numerical Simulation for Aluminium Alloys

2017 ◽  
Vol 17 (3) ◽  
pp. 23-26 ◽  
Author(s):  
M. Brůna ◽  
D. Bolibruchová ◽  
R. Pastirčák
Keyword(s):  
Free Surface ◽  
Aluminium Alloys ◽  
Oxide Films ◽  
Front Tracking ◽  
Gating System ◽  
Liquid Aluminium ◽  
Surface Time ◽  
Filling Pattern ◽  
Entrained Air ◽  
Flow Experiments

Abstract Pouring of liquid aluminium is typically accompanied by disturbance of the free surface. During these disturbances, the free surface oxide films can be entrained in the bulk of liquid, also pockets of air can be accidentally trapped in this oxide films. The resultant scattering of porosity in castings seems nearly always to originate from the pockets of entrained air in oxide films. Latest version of ProCast software allows to identify the amount of oxides formed at the free surface and where they are most likely to end-up in casts. During a filling calculation, ProCast can calculate different indicators which allow to better quantify the filling pattern. The fluid front tracking indicator “Free surface time exposure” has the units [cm2*s]. At each point of the free surface, the free surface area is multiplied by the time. This value is cumulated with the value of the previous timestep. In addition, this value is transported with the free surface and with the fluid flow. Experiments to validate this new functions were executed.

scholarly journals The Influence of Impeller Geometry on the Gas Bubbles Dispersion in Uro-200 Reactor – RTD Curves / Wpływ Rodzaju Wirnika Na Dyspersję Pęcherzyków Gazowych W Reaktorze URO-200 – Krzywe Mieszania

2015 ◽  
Vol 60 (4) ◽  
pp. 2887-2894 ◽  
Author(s):  
M. Saternus ◽  
T. Merder ◽  
J. Pieprzyca
Keyword(s):  
Flow Rate ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Gas Bubbles ◽  
Refining Process ◽  
Inert Gas ◽  
Impeller Speed ◽  
Batch Reactors ◽  
Liquid Aluminium ◽  
Impeller Geometry

URO-200 reactor belongs to batch reactors used in refining process of aluminium and its alloys in polish foundries. The appropriate level of hydrogen removal from liquid aluminium can be obtained when the mixing of inert gas bubbles with liquid metal is uniform. Thus, the important role is played by the following parameters: flow rate of refining gas, geometry of the impeller, rotary impeller speed. The article presents the results of research conducted on physical model of URO-200 reactor. The NaCl tracer was introduced to water (modelling liquid aluminium) and then the conductivity was measured. Basing on the obtained results the Residence Time Distribution (RTD) curves were determined. The measurements were carried out for two different rotary impellers, flow rate equaled 5, 10, 15 and 20 dm3/min and rotary impeller speed from 250 to 400 rpm every 50 rpm.

Cooling rate dependence of solidification for liquid aluminium: a large-scale molecular dynamics simulation study

2016 ◽  
Vol 18 (26) ◽  
pp. 17461-17469 ◽  
Author(s):  
Z. Y. Hou ◽  
K. J. Dong ◽  
Z. A. Tian ◽  
R. S. Liu ◽  
Z. Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Cooling Rate ◽  
Simulation Study ◽  
Large Scale ◽  
Solidification Process ◽  
Molecular Dynamics Method ◽  
Dynamics Simulation ◽  
Liquid Aluminium ◽  
Dynamics Method

The effect of the cooling rate on the solidification process of liquid aluminium is studied using a large-scale molecular dynamics method.

Structures of Liquid Aluminium under High Pressure

2001 ◽  
Vol 18 (4) ◽  
pp. 495-497 ◽  
Author(s):  
Li Hui ◽  
Wang Guang-Hou ◽  
Bian Xiu-Fang ◽  
Zhang Lin
Keyword(s):  
High Pressure ◽  
Liquid Aluminium
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