[SY-F8] Symposium F-8

[SY-F8] Thermo-kinetic modeling of long-term precipitate evolution in heat-resistant alloys

^○Jae-Hyeok Shim¹, Magdalena Speicher², Mahesh Chandran³, Woo-Sang Jung¹ (1.Korea Institute of Science and Technology, Korea, 2.Materials Testing Institute, Germany, 3.Indo-Korea Science and Technology Centre, India)

There is an urgent need to improve the thermal efficiency of fossil fuel power plants by raising the operation temperature and pressure in order to reduce CO₂ emission as well as the cost of fuel. Plant operation at higher temperatures inevitably requires the development of heat-resistant alloys with a higher creep strength. There has recently been an increasing interest in applying advanced heat-resistant alloys to fossil fuel power plants in order to raise their operation temperature. The important role of precipitation in the achievement of good creep properties of heat-resistant alloys has long been recognized. One of the most effective ways for improving the creep properties is to uniformly distribute fine precipitates with a good long-term stability at elevated temperatures. The experimental investigation of the long-term precipitate evolution behavior in heat-resistant alloys have not often been performed, although it is important in understanding the creep properties. In addition to experimental approaches, there have recently been a few attempts to simulate the precipitation kinetics in heat-resistant alloys. The purpose of this study is to simulate the long-term precipitate evolution in various heat-resistant alloys such as ferritic/martensitic and austenitic steels and nickel alloys using the MatCalc software, which operates based on the classical nucleation theory and evolution equations derived from the thermodynamic extremum principle that maximizes the dissipation rate of the total Gibbs energy of the system. The simulation results, such as the precipitation sequence and the precipitate size, will be compared with experimental observations.