scholarly journals Kinetic Simulations of Diffusion-Controlled Phase Transformations in Cu-Based Alloys

2018 ◽  
Vol 15 ◽  
pp. 1-22 ◽  
Author(s):  
Ying Tang ◽  
Qing Chen ◽  
Anders Engström
Keyword(s):  
Phase Transformations ◽  
Computer Aided Design ◽  
Copper Alloys ◽  
Liquid Solution ◽  
Calphad Approach ◽  
Diffusion Controlled ◽  
Mobility Database ◽  
Thermo Calc Software ◽  
Aided Design ◽  
Kinetics Of

In this chapter, we present computational kinetics of diffusion-controlled phase transformations in Cu-based alloys, which becomes possible only most recently due to the establishment of the first atomic mobility database (MOBCU) for copper alloys. This database consists of 29 elements including most common ones for industrial copper alloys. It contains descriptions for both the liquid and Fcc_A1 phases. The database was developed through a hybrid CALPHAD approach based on experiments, first-principles calculations, and empirical rules. We demonstrate that by coupling the created mobility database with the existing compatible thermodynamic database (TCCU), all kinds of diffusivities in both solid and liquid solution phases in Cu-based alloys can be readily calculated. Furthermore, we have applied the combination of MOBCU and TCCU to simulate diffusion-controlled phenomena, such as solidification, nucleation, growth, and coarsening of precipitates by using the kinetic modules (DICTRA and TC-PRISMA) in the Thermo-Calc software package. Many examples of simulations for different alloys are shown and compared with experimental observations. The remarkable agreements between calculation and experimental results suggest that the atomic mobilities for Cu-based alloys have been satisfactorily described. This newly developed mobility database is expected to be continuously improved and extended in future and will provide fundamental kinetic data for computer-aided design of copper base alloys.

scholarly journals Effects of Austenitization Temperature and Pre-Deformation on CCT Diagrams of 23MnNiCrMo5-3 Steel

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5116
Author(s):  
Ivo Schindler ◽  
Rostislav Kawulok ◽  
Petr Opěla ◽  
Petr Kawulok ◽  
Stanislav Rusz ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Deformation Temperature ◽  
True Strain ◽  
Austenitization Temperature ◽  
Diffusion Controlled ◽  
Significant Acceleration ◽  
Wide Range ◽  
Mean Grain Size ◽  
Cct Diagrams ◽  
Kinetics Of

The combined effect of deformation temperature and strain value on the continuous cooling transformation (CCT) diagram of low-alloy steel with 0.23% C, 1.17% Mn, 0.79% Ni, 0.44% Cr, and 0.22% Mo was studied. The deformation temperature (identical to the austenitization temperature) was in the range suitable for the wire rolling mill. The applied compressive deformation corresponded to the true strain values in an unusually wide range. Based on the dilatometric tests and metallographic analyses, a total of five different CCT diagrams were constructed. Pre-deformation corresponding to the true strain of 0.35 or even 1.0 had no clear effect on the austenite decomposition kinetics at the austenitization temperature of 880 °C. During the long-lasting cooling, recrystallization and probably coarsening of the new austenitic grains occurred, which almost eliminated the influence of pre-deformation on the temperatures of the diffusion-controlled phase transformations. Decreasing the deformation temperature to 830 °C led to the significant acceleration of the austenite → ferrite and austenite → pearlite transformations due to the applied strain of 1.0 only in the region of the cooling rate between 3 and 35 °C·s−1. The kinetics of the bainitic or martensitic transformation remained practically unaffected by the pre-deformation. The acceleration of the diffusion-controlled phase transformations resulted from the formation of an austenitic microstructure with a mean grain size of about 4 µm. As the analysis of the stress–strain curves showed, the grain refinement was carried out by dynamic and metadynamic recrystallization. At low cooling rates, the effect of plastic deformation on the kinetics of phase transformations was indistinct.

Some Perspectives in the Modelling of Biological Treatment of Wastewaters

1982 ◽  
Vol 14 (1-2) ◽  
pp. 227-240 ◽  
Author(s):  
A James
Keyword(s):  
Computer Aided Design ◽  
Biological Treatment ◽  
Activated Sludge Process ◽  
Variable Yield ◽  
Physical Description ◽  
Fixed Film ◽  
Recent Developments ◽  
Operational Models ◽  
Aided Design ◽  
Kinetics Of

This paper reviews some recent developments in the modelling of the biological treatment of wastewaters with particular reference to the activated sludge process. The bacterial kinetics of completely-mixed reactors are discussed emphasising the need to have a variable yield. Modelling complications of variable yields are noted in particular those caused by de-coupling growth and substrate utilization. Other methods of solution are considered including relating the yield to the sludge age. Modelling developments in fixed-film reactors are briefly examined, comparing the refinement in the chemical/physical description with the lack of refinement in the ecological representation. The aims of modelling are reviewed and some fruitful areas in operational models and computer-aided-design are identified.

scholarly journals Evaluation of Biodegradable PVA-Based 3D Printed Carriers during Dissolution

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1350
Author(s):  
Bálint Basa ◽  
Géza Jakab ◽  
Nikolett Kállai-Szabó ◽  
Bence Borbás ◽  
Viktor Fülöp ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Pharmaceutical Manufacturing ◽  
In Vitro Dissolution ◽  
Uv Spectrophotometry ◽  
Test Results ◽  
Computer Design ◽  
3D Printed ◽  
Aided Design ◽  
Kinetics Of

The presence of additive manufacturing, especially 3D printing, has the potential to revolutionize pharmaceutical manufacturing owing to the distinctive capabilities of personalized pharmaceutical manufacturing. This study’s aim was to examine the behavior of commonly used polyvinyl alcohol (PVA) under in vitro dissolution conditions. Polylactic acid (PLA) was also used as a comparator. The carriers were designed and fabricated using computer-aided design (CAD). After printing the containers, the behavior of PVA under in vitro simulated biorelevant conditions was monitored by gravimetry and dynamic light scattering (DLS) methods. The results show that in all the dissolution media PVA carriers were dissolved; the particle size was under 300 nm. However, the dissolution rate was different in various dissolution media. In addition to studying the PVA, as drug delivery carriers, the kinetics of drug release were investigated. These dissolution test results accompanied with UV spectrophotometry tracking indirectly determine the possibilities for modifying the output of quality by computer design.

CAD Of Anticorrosive Protection Of Steel Structures

2019 ◽  
pp. 18-23
Keyword(s):  
Protective Coating ◽  
Computer Aided Design ◽  
Steel Structures ◽  
Cost Effective ◽  
Operating Conditions ◽  
Computational Tool ◽  
Protection Method ◽  
Cost Effective Method ◽  
The Cost ◽  
Aided Design

The choice of cost-effective method of anticorrosive protection of steel structures is an urgent and time consuming task, considering the significant number of protection ways, differing from each other in the complex of technological, physical, chemical and economic characteristics. To reduce the complexity of solving this problem, the author proposes a computational tool that can be considered as a subsystem of computer-aided design and used at the stage of variant and detailed design of steel structures. As a criterion of the effectiveness of the anti-corrosion protection method, the cost of the protective coating during the service life is accepted. The analysis of existing methods of steel protection against corrosion is performed, the possibility of their use for the protection of the most common steel structures is established, as well as the estimated period of effective operation of the coating. The developed computational tool makes it possible to choose the best method of protection of steel structures against corrosion, taking into account the operating conditions of the protected structure and the possibility of using a protective coating.

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