Studium termofyzikálních a termodynamických vlastností kvaternárních systémů na bázi Fe C O X(Y), (X, Y = Cr, Ni) metodami termické analýzy

Abstract

The study of Fe-based systems is currently still a very relevant topic. The subject of study are complex systems such as steels and also simple alloys containing carbon and other individual alloying or admixed elements. Alloying elements such as chromium, nickel and also admixed elements such as oxygen and sulfur are very often part of the complex and simple composition of these alloys. In the dissertation, the study is focused on Fe–C–Cr, Fe–C–Ni, Fe–C–Cr–Ni systems with a minor content of other elements, e.g. oxygen. The subject of the study was the preparation and subsequent characterization of the prepared ternary and quaternary systems with a graded composition of the key elements represented (C, Cr and Ni). The aim of the dissertation was mainly to investigate the relationship between the chemical composition and the resulting properties. Model alloys with graded amounts of individual elements were prepared for the dissertation: C (0,120 to 1,563 wt. %), Cr (0,011 to 4,835 wt. %) and Ni (0,001 to 4,495 wt. %). In the work, the activities were focused on the study of thermophysical and thermodynamic properties and behavior. Knowledge of this key area (heating/cooling behavior data) and other data can often be obtained using modelling, but the results are often misleading in many ways. As part of the dissertation, experimental techniques leading to the acquisition of key thermophysical and thermodynamic data of the above-mentioned systems were used, such as heat capacities, enthalpies and their dependence on temperature, heat of phase transformations and temperature of phase transformations, both in low-temperature and in high-temperature region (25 to 1580 °C, both solid and liquid phase - melt) were studied. The methods of thermal analysis and calorimetry DTA (Differential Thermal Analysis, Setaram SETSYS 18TM device) and DSC (Differential Scanning Calorimetry, Setaram MHTC 96 Line and Setaram Sensys Evo TG/3D DSC/HP devices) were used for the experimental part of the work. The experimental results were compared, confronted and discussed with the results of thermodynamic modeling using thermodynamic SW Thermo–Calc and thermodynamic–kinetic SW JMatPro. The studied area is significant both from a fundamental point of view (impairment of primary/basic knowledge) and also with regard to the application area (for heating/cooling processes, casting, thermal and mechanical processing) and also in the area of modeling these processes through the implementation of data into simulation software. The obtained data are also important for the possible addition of thermodynamic and kinetic databases of SW simulations and the creation of an own database.