[SY-F8] Symposium F-8

[SY-F8] Modelling of grain boundary segregation and precipitation in multi-component Al alloys subjected to heat treatment

^○Dongdong Zhao¹, Sylvain Gouttebroze², Jesper Friis³, Yanjun Li¹ (1.Norwegian University of Science and Technology (NTNU), 7491, Trondheim , Norway, 2.SINTEF Materials and Chemistry, 0314 Oslo, Norway, 3.SINTEF Materials and Chemistry, 7491 Trondheim, Norway)

A newly developed modelling framework which accounts for grain boundary (GB) segregation and precipitation in multi-component Al alloys subjected to cooling and subsequent heat treatments is presented. Within this framework, both the equilibrium and non-equilibrium segregation mechanisms are considered to predict the solute and vacancy segregations towards GBs. In the model of non-equilibrium segregation, GBs are considered as ideal sinks for vacancy annihilation. The CALPHAD (CALculations pf PHAse Diagrams) approach is implemented to supply the important thermodynamic and kinetic data of multi-component Al alloys as input for the model. The present framework is expected to predict the solute and vacancy segregations at GBs in multi-component Al alloys during typical heat treatment (e.g. quenching, ageing) processes. It is shown that the variation of vacancy and solute segregation behavior at GBs as a function of heat treatment or microstructure variables, i.e. solution/ageing temperature, cooling rate, grain size, can be well described within the present model. Based on the segregation of solute elements, preliminary precipitation behavior at GBs and bulk are predicted using the Kampmann-Wagner numerical approach. The simulation results have been compared with experimental observations. This work is supposed to provide a preliminary theoretical understanding towards the GB segregation and precipitation in multi-component Al alloys subjected to various cooling and subsequent heat treatment processes.