Thermodynamic Optimization And Application In The Alloy Systems

Thermodynamics is of great significance on the studies in the field of materials science. With the computer coupling of thermodynamics and phase diagrams the CALPHAD technique came into being, through which thermodynamic studies on the substance systems could be performed.Intermetallic compounds formed between Rare Earths (RE) and metals have good prospect, which can be used as the new type materials such as superconductive materials. At present a lot of work has been done to investigate the structures and stabilities of these compounds. However, studies on their thermodynamic properties are limited and experimental data are greatly scarce. Moreover, there is no check of the consistency between thermodynamic data and their suggested phase diagrams. By means of the CALPHAD approach the parameters of Gibbs energy functions were optimized and assessed with different experimental information available. Reasonable and consistent thermodynamic descriptions of the Gibbs energy functions of various phases in the systems were obtained, as well as the accurate data of phase diagrams. These functions could be stored as the database of the intermetallic compounds that can provide valuable references for the designing of Rare-Earth alloys and crafts. In the present work the phase diagrams and thermodynamic data of La-In, Au-La and Ag-Y binary alloy systems were thermodynamically optimized and assessed using the computer software THERMO-CALC. Consistent sets of thermodynamic parameters were obtained and good agreement was derived between the calculated and experimental results.Thermodynamic analysis together with the studies of phase diagrams could help to solve the problems in the productive practice. Continuous galvanizing is one kind of the hot-dip galvanizing. And aluminum is one of the most important added elements in the zinc bath, which has direct effect on the quality of galvanizing. But it is still difficult to measure and control the content of aluminum in the zinc bath. Foreign researchers have proposed some solutions but the satisfactory results can not be gained. In this work a program was written with the graphical user interfaces onthe basis of thermodynamic analysis , by which the solubility curves of iron are analyzed in the Fe-Zn-Al system. Moreover the application of thermodynamic analysis makes it implemented to calculate the content of the effective aluminum in the zinc bath, which can do good to control the aluminum content in the galvanizing industry.