Au-Sn-X (X = Co, La, Er) system optimization and calculation of the thermodynamic

Title: Au-Sn-X (X = Co, La, Er) system optimization and calculation of the thermodynamicAuthor: Dong Hong-qunDegree-granting units: Central South UniversityKeywords: gold solder;; phase diagram calculations;; Au-Er binary system;; Au-Sn-Co ternary system;; Au-Sn-La ternary systemSummary:

Because of its excellent ductility, the perfect anti-corrosion and oxidation resistance, excellent electrical conductivity, thermal conductivity, etc., Au-20Sn is widely used in optoelectronic packaging, aerospace and other fields. However, Au is expensive, Magnetic lifter so how to add some other alternative to alloy-element Au, is the solder development.

Recent studies have found that rare earth (RE) can improve the mechanical properties and solder wettability, solder joints clean grain boundary, to improve the fatigue strength of solder joints. Therefore, combining the advantages of China's rare earth-rich, research-related system phase diagram, for the design of the new Au-Sn-based solder is important.

This combined with the existing experimental data and phase diagram of compounds formed first-principles calculation of enthalpy, calculated using CALPHAD technology to optimize the Au-Co, Au-La and Au-Er three binary systems, fixed Au-Sn and Co- Sn two binary system; extrapolation optimized Au-Sn-Co system; a simple extrapolation of the Au-Sn-La ternary system; and initially were set up various systems of self-consistent thermodynamic database, the main results obtained are as follows:

1 calculated using the phase diagram (CALPHAD) method, using the Thermo-Calc thermodynamic software package to optimize and calculate the Au-Co, Au-La and Au-Er three binary systems. The occasion of the liquid phase with the end of which alternative solution model, all the intermediate compounds are stoichiometric model, the calculated phase equilibria and thermodynamic data are in good agreement with experimental data.

(2) using first-principles calculation of the enthalpy of formation of compounds, combined with CALPHAD method, using Thermo-Calc thermodynamic software fixes Au-Sn binary system; better fit three yuan for the correlation, fine-tuning of the Sn-Co two yuan http://www.999magnet.com/products/131-magnetic-lifter Department of thermodynamic parameters.

3 calculated using the phase diagram (CALPHAD) method, using Pandat extrapolation package optimized thermodynamic Au-Sn-Co and a simple extrapolation of the two Au-Sn-La ternary system. According to the experimental data, we found that some compounds in the third element of the solubility increases, Au-Sn-Co system, the emergence of a meet-stoichiometric ternary compounds. The calculated phase diagram data and experimental results.Degree Year: 2010