Cross-scale analysis of nickel Superalloy fatigue using Markov state model-molecular dynamics method

Abstract

Molecular dynamics (MD) simulation is an advanced method in microscale modelling of material but it depends on the complexity of the model. The performance of MD simulation is poor once the model size is huge. To accelerate the computing of MD simulation, the Markov state model (MSM) can be applied because of the ability to predict a future state of a stochastic system. With the advantage of MSM and MD applied in material modelling, a good result could be expected where the time scale limitation of MD simulation is bridged by MSM method. In this research, an MSM method based on the MD microstates in which a nickel superalloy's atomic model arrangements and their microstructure evolution have been treated with the Markov properties is presented. This MSM is based and classified by a dislocation model which is a fundamental of the microstructural tessellation evolution. The results indicate that the microstructure evolution in a situation of energy minimisation favours the formation of new faults alongside existing ones. And dislocation accumulation on the grain boundary was observed during fatigue resolving. Some dislocations formatted and grown in the middle of coarse grain and penetrated through the grain.