Effect of mismatch degree on mechanical properties of Ni-based single crystal alloy under force-temperature coupling

Abstract

Mismatch degree has an important effect on the mechanical properties of Ni-based single crystal alloys. However, the effect of mismatch degree on mechanical properties under force-temperature coupling is unclear. Thus, we used molecular dynamics method to study mechanical properties and microstructural evolution of Ni-based single crystal alloy. The interface dislocation network and mechanical properties under different positive mismatches are discussed respectively. We found that the lower the mismatch degree, the more regular the dislocation network is, which can effectively prevent the dislocation motion and increase the strength. Meanwhile, when the mismatch degree is less than 1.43, the yield strength gradually decreases with the increase of the mismatch degree. When the mismatch degree is 1.43, the yield strength reaches the minimum value. Moreover, the lower interface energy can increase the yield strength of nickel-based single crystal alloy, and the yield strength decreases with the increase of interface energy. To compare the influence of positive and negative mismatch on mechanical properties and microscopic evolution, the yield stress of Ni-based single crystal alloy increases with the increase of mismatch, but the change is not significant. At the negative mismatch degree, the yield stress decreases as the mismatch decreases. When the absolute value of the mismatch is the same, the yield stress at a positive mismatch of 0.33% is greater than the yield stress at a negative mismatch of −0.33%.