Ni/Ni3Al interface-dominated nanoindentation deformation and pop-in events

Nickel-based single crystal alloys have excellent mechanical properties due to its unique two-phase structure and interface. Therefore, molecular dynamics methods were used to simulate nanoindentation and microstructural evolution. We found the indenter reaction force and hardness of the Ni3Al phase is the largest. The pop-in event in Ni3Al phase is more obvious than that in the Ni phase and Ni/Ni3Al phase. Because lots of dislocations in the Ni3Al phase break through the barrier of the interface and cut into the Ni phase, while dislocations in the Ni phase only slip inside the Ni phase. Moreover, we found that the position of the starting point of the adhesion force recovery is mainly related to the elastic recovery of the material. The stronger the elastic recovery of the phase, the smaller the depth value corresponding to the starting point of the recovery. We further studied the variation of potential energy with indentation depth and found that the change of wave trough of the load-displacement (P-h) curve is related to stacking fault energy. This study has important theoretical guiding significance for the in-depth understanding and engineering application of the mechanical properties of nickel-based single crystal alloys.

Automated summary

Nickel-based single crystal alloys have excellent mechanical properties due to their unique structure and interface. By simulating nanoindentation and microstructural evolution, the hardness of the Ni3Al phase was found to be the highest and dislocations can penetrate the interface into the Ni phase. Furthermore, the starting point of adhesion force recovery was found to be related to the material's elastic recovery, and the variation of potential energy was related to stacking fault energy.