scholarly journals Thermodynamics and Agglomeration Behavior on Spinel Inclusion in Al-Deoxidized Steel Coupling with Mg Treatment

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 900 ◽  
Author(s):  
Cao ◽  
Wang ◽  
Yuan ◽  
Jin ◽  
Sridhar
Keyword(s):  
Phase Transformation ◽  
Liquid Phase ◽  
Molten Steel ◽  
Lattice Mismatch ◽  
Dominant Role ◽  
Al Content ◽  
Agglomeration Process ◽  
Spinel Inclusion ◽  
Calculation Results ◽  
Mg Content

There are many types of non-metallic MgAl2O4 inclusions observed in Al-deoxidized steel coupling with Mg treatment, including single-particle MgAl2O4, agglomerated MgAl2O4, and MgAl2O4-MnS. Thermodynamic calculation shows that MgAl2O4 precipitates in the liquid phase. The phase transformation follows liquid + Al2O3 + MgAl2O4 → liquid + MgAl2O4 → liquid + MgO + MgAl2O4 → liquid + MgO with the Mg content increasing when the Al content is a constant in molten steel, and it is in agreement with the experimental results for the formation of MgAl2O4 in molten steel. The calculation results of various attractive forces between two particles show that the cavity bridge force plays a dominant role in the agglomeration process and results in the agglomerated MgAl2O4. The lattice mismatch calculation result shows that MgAl2O4 can provide effective sites for MnS nucleating in steel.

Thermodynamics Software Development on Composition Prediction of Inclusions in Molten 430 Stainless Steel

2012 ◽  
Vol 430-432 ◽  
pp. 337-340
Author(s):  
Ying Zhuang ◽  
Zhou Hua Jiang ◽  
Yang Li
Keyword(s):  
Stainless Steel ◽  
Software Development ◽  
Phase Diagrams ◽  
Molten Steel ◽  
Equilibrium Phase ◽  
Al Content ◽  
430 Stainless Steel ◽  
Si Content ◽  
Mg Content

Thermodynamics software on inclusions prediction in 430 stainless steel was developed with Matlab and VC++. The inclusions’ composition could be predicted by composition of molten steel input, and equilibrium phase diagrams of MgO•Al2O3, 2MgO•SiO2, 3Al2O3•2SiO2 and 2Al2O3•2MgO•5SiO2 were displayed on the main interface simultaneously. The following predicted results by inputing experiments data at 1873 K can be gained that When Si content is 3.9×10-3and Al content is 3.5×10-4, MgO•Al2O3 spinel inclusions is unformed in case of Mg content with larger than 1.71×10-5; while MgO•Al2O3 spinel inclusions transformed into 2Al2O3•2MgO•5SiO2 inclusions in case of Mg content being less than 2.9×10-8. The predicted results of software fit well with the experiment results, Therefore, the software can provide some results for controlling the composition of inclusions in molten steel.

Microstructure Characteristic of AZ31/7005 Joints by GTAW with Filler Wire of Mg-Al Alloy

2014 ◽  
Vol 1004-1005 ◽  
pp. 168-171
Author(s):  
Hong Yan Du ◽  
Yaj Jang Li ◽  
Juan Wang
Keyword(s):  
Solid Solution ◽  
Intermetallic Compounds ◽  
Fusion Zone ◽  
Weld Zone ◽  
Dissimilar Materials ◽  
Eutectic Structure ◽  
Al Alloy ◽  
Test Results ◽  
Al Content ◽  
Mg Content

Mg/Al dissimilar materials were welded successfully by GTAW with SAlMg-1 and SAlMg-2 welding wire of Mg-Al system. The nice weld shape and free defects of joints are obtained. The test results indicated that continuous lamellar intermetallic compounds is not found The structure of Mg side in the fusion zone is composed of α-Mg solid solution+ β-Al12Mg17eutectic structure and precipitates β-A112lMg17on the grain boundary. The structure in the weld zone is mainly α-Mg solid solution + β-A112lMg17solid solutions. Mg and Al content are stable in the fusion zone of Mg side. However, in the weld zone of Mg side the Mg content is decreased gradually, and the Al content is increased that reaches a stable level in the weld zone of Al side. As a result, when Mg content in the wire can hold a proper level, the intermetallic compounds will be controlled effectively, and the performance of AZ31/7005 welding joint can be improved.

Solidification of Al-Pb Alloy under the Effect of Micro-Alloying Element Ti and C

2016 ◽  
Vol 879 ◽  
pp. 2439-2443 ◽  
Author(s):  
Qian Sun ◽  
Hong Xiang Jiang ◽  
Jiu Zhou Zhao
Keyword(s):  
Phase Transformation ◽  
Liquid Phase ◽  
Microstructure Evolution ◽  
Solidification Process ◽  
Miscibility Gap ◽  
Kinetic Behavior ◽  
Number Density ◽  
Alloying Element ◽  
Refinement Efficiency ◽  
Line Temperature

Experiments were carried to investigate the effect of TiC on the solidification process and microstructure of Al-Pb alloys. It is demonstrated that TiC particles are effective inoculants for the nucleation of the Pb-rich droplets during cooling an Al-Pb alloy in the miscibility gap. A model describing the kinetic behavior of TiC particles in the melt and the liquid-liquid decomposition of Al-Pb was developed. The dissolution, coarsening and precipitation processes of TiC particles as well as the microstructure evolution during the liquid-liquid phase transformation of an Al-Pb alloy were calculated. The numerical results indicate that what determines the refinement efficiency of TiC particles on the Pb-rich droplets/particles is the number density of TiC particles in the melt cooled to the binodal line temperature of the Al-Pb alloy. If the number density of TiC particles in the melt before the beginning of the liquid-liquid decomposition is high enough, the addition of TiC causes a refinement of the Pb-rich droplets/particles and promotes the formation of Al-Pb alloys with a well dispersed microstructure.

The ISSMGE Kerry Rowe Lecture: The role of diffusion in environmental geotechnics

2014 ◽  
Vol 51 (11) ◽  
pp. 1219-1242 ◽  
Author(s):  
Charles D. Shackelford
Keyword(s):  
Liquid Phase ◽  
Dominant Role ◽  
Compacted Clay ◽  
Clay Liners ◽  
Permeable Membrane ◽  
Waste Containment ◽  
Phase Diffusion ◽  
High Level ◽  
The Impact

Diffusion of contaminants can play a significant if not dominant role in many applications encountered within the field of environmental geotechnics. The objective of this paper is to provide an overview of the important role diffusion plays in such applications. The presentation proceeds from a historical perspective, beginning with the recognition in the late 1970s to early 1980s that diffusion may be an important process in assessing contaminant migration through low-permeability barriers in waste containment applications. Data from the literature and simplified model simulations are used to illustrate under what conditions diffusion is important, and the significance of diffusion is illustrated with respect to different barrier components and types of barriers used in waste containment applications. The barriers considered include natural clays, compacted clay liners, geomembranes, geosynthetic clay liners, composite liners, vertical cutoff walls, subaqueous caps for contaminated sediments, and highly compacted bentonite buffers for high-level radioactive waste containment. The significance of semi-permeable membrane behavior on liquid-phase diffusion through bentonite-based barriers also is highlighted. The potential importance of matrix diffusion as an attenuation mechanism for contaminant transport is illustrated, and the roles of both liquid-phase and gas-phase diffusion under unsaturated conditions are discussed. Finally, the role of diffusion in terms of remediation applications is illustrated via an example analysis illustrating the impact of reverse matrix or back diffusion on the effectiveness of pump-and-treat remediation, as well as via a summary of several diffusion-based models commonly used to describe the leaching of contaminants from a variety of stabilized–solidified waste forms.

Sign in / Sign up

Export Citation Format

Share Document