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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Modelování fázového složení žárupevných ocelí a jejich spojů / Modelling of Phase Composition of Heat Resistant Steels and their Welds

Dvořáček, Ondřej Unknown Date (has links)
This work deals with the effects of high temperature exposition of low alloyed creep resistant steels on their structural stability and structural stability of their weld joint. The theoretical part of this work gives an overview of creep resistant steels considering their chemical and phase composition and their connection to high temperature mechanical properties. The CALPHAD method is presented as generally accepted approach for equilibrated calculations and Thermo-Calc and DICTRA software packages are introduced as CALPHAD applications. Thermo-Calc software is used for calculation of phase composition of the examined materials and for calculation of the phase diagrams. Software DICTRA is used for simulations of diffusion controlled phase reactions in the analysed weld. Experimentally one weld joint of the steels 15 128 and 15 313 has been studied after four different annealing procedures. The experimental results include chemical profiles across the welds, microhardness profiles and metallographic analysis of significant regions of the welds. These experimental results are compared with the simulation results. The comparison shows a reasonable agreement between experimental and simulation data.
32

Development of a Primary Solidification Mode Diagram for Austenitic Stainless Steel Weld Metals Using CALPHAD-Based Modeling

Sutton, Benjamin James January 2021 (has links)
No description available.
33

Theoretical and Experimental Study of the Co-Cr-Mo System

Lu, YiYao January 2011 (has links)
The thermodynamic properties of the Co-Cr-Mo ternary system have been described. Available experimental data on the system have been assessed and applied to optimize the parameters used in the thermodynamic models within the Calphad method. Meanwhile, samples were made by the powder metallurgical process and heat treated (sintered) at 1573 K to investigate the phase diagram data related to the intermetallic phases, such as σ, μ and R phases present in the system. With the optimized thermodynamic description, we are able to fit most of the experimental data in the literature and from this work. However, the one phase field of R is too narrow in the present description. Furthermore, at 1573 K the extension of the phase boundary of σ toward the Co corner needs to be improved. In addition, the calculated phase diagram at 1573 K shows a fcc-bcc-σ three-phase equilibrium near the Co-Cr binary side. This is not shown in the experimentally determined ternary phase diagram but is necessary in order to match the recent data on the Co-Cr binary system.
34

Corrosion of Ni-Fe-Cr-Mo-W-X non-equimolar multi-principal element alloys

Panindre, Anup January 2021 (has links)
No description available.
35

Exploration of New High Entropy Alloys (HEA) and HEA-reinforced Metal Matrix Composites Using a CALPHAD-based Approach

Huang, Xuejun January 2021 (has links)
No description available.
36

Modelling study of Ti64 and Ti6242 as a first approach to understand their additive manufacturing behaviors

De Monte, Clara January 2023 (has links)
Aerospace and aeronautics industries push forward the research to improve constantly the quality, safety, and cost of flights. The main ways of improving products are to create lighter and better components, under a highly controlled processing from the research and development to the production at a big scale.  To achieve those goals, new processes and new materials are constantly created by engineers. In this perspective, titanium alloys have been developed and studied as they provide good mechanical properties and low density. To reduce the production costs and waste due to machining, additive manufacturing has started to be implemented on the manufacturing chains. Titanium alloys seemed to react very well to additive manufacturing, but there are still some problematics that need to be answered.  The main problematic of this thesis comes from the process development cell. It has been stated that two different titanium-based alloys, Ti-6Al-4V and Ti-6Al-2Mo-4Zr-2Sn, showed the same behavior under additive manufacturing, which is not an evident statement. Therefore, the goal of this work will be to understand the behavior of those two alloys by simulations and use of key parameters in order to model the process in a proper and accurate way.
37

THE SOLUBILITIES OF CARBON AND NITROGEN IN IRON, NICKEL AND TITANIUM-BASED ALLOYS UNDER PARAEQUILIBRIUM CONDITIONS

Gu, Xiaoting January 2008 (has links)
No description available.
38

Low Temperature Carburization of Ferritic Stainless Steels

Katz, Joshua H. January 2009 (has links)
No description available.
39

Phase Transformations Accompanying Low-Temperature Carburization of Martensitic Stainless Steels under Paraequilibrium Conditions

Lee, Chihoon 30 January 2012 (has links)
No description available.
40

Thermodynamic modelling as applied to the development of TRIP-Matrix-Composite materials: The Fe–Mg–Mn–Ti–Zr–O system

Saenko, Ivan 26 January 2021 (has links)
This thesis performed within the Collaborative Research Center 799 describes a development of the metal-ceramic thermodynamic databases as applied to the design of the TRIP-Matrix-Composite materials. A wide range of theoretical and experimental investigations have been carried out in the relevant systems of Fe–Mg–Zr–O, Mg–Ti–Zr–O and Mg–Mn–Zr–O. Thermodynamic data were obtained using experimental methods of calorimetry and ab-initio calculations. Phase relations in the constituent binary and ternary systems have been studied using different types of static and dynamic methods. The obtained results allowed an assessment of thermodynamic parameters of the aforementioned systems using CALPHAD approach. The thermodynamic calculations have been performed to predict interfacial reactions within the composite material as well as to made recommendations for the design and further development of production processes for TRIP-Matrix-Composite materials.

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