Thermodynamic And Kinetic Study Of Ni-Al-X(X=Re&Ru) Ternary System

Nickel-based superalloys are extremely important alloys in aerospace field.They are mainly used to make complex high-temperature parts for their long life,good corrosion and resistance,especially their excellent overall performance at high temperature.At present,the thermodynamic and kinetic studies of nickel-Based superalloys are transferring from traditional method to CALPHAD method with the development of materials computational science,which combined computational technique with experimental measurement.The thermodynamic database and kinetic database are established by making use of various experimental data and first-principles calculations.As a result,computational simulation and theoretical prediction can be realized.This article is aimed to discuss the phase diagrams and diffusion kinetic of NiAl-X(X=Re&Ru)ternary system,which based on the computational thermodynamic and computational kinetic.In the present work,binary systems have been evaluated amply and relevant thermodynamic parameters those can be applied in multi-component systems have been achieved.The isothermal sections of the Ni-Al-Re/Ru ternary system at 1273 K and1473K were constructed experimentally by examining equilibrated alloys and diffusion couples,through which the phase equilibria were determined by Energy Dispersive Spectroscopy(EDS)and Electron Probe Micro-Analysis(EPMA).Based on the measured phase equilibria and first-principles calculation data,the model parameters formulating the Gibbs energies of various phases of the binary and ternary systems of Ni-Al-Re/Ru were assessed by the CALPHAD method with the Thermo-Calc software.A set of self-consistent thermodynamic parameters of the Ni-Al-Re/Ru system has been obtained successfully and can be extended to multi-component thermodynamic databases for superalloys,and provide a thermodynamic reference for dynamic optimization.This study used diffusion couple method and EPMA technique to gain the interdiffusion coefficients of the fcc phase for Ni-Al-Re/Ru ternary system by applying the Whittle-Green method.The interdiffusion data was used to assess the mobility of the fcc Ni-Al-Re/Ru in the DICTRA software.The calculated coefficients and the simulated concentration profiles were consistent well with the experiment data,which indicates that the optimized kinetic parameters are reliable to establish the kinetic database of Ni-based superalloys.