TiB2纳米颗粒对Ni60Cr21Fe19合金快速定向凝固过程微观组织和力学性能的影响:分子动力学研究OACSTPCD

Molecular dynamics(MD)simulations are employed to delve into the multifaceted effects of TiB2 nanoparticles on the intricate grain refinement mechanism,microstructural evolution,and tensile performance of Inconel 718 superalloys during the rapid directional solidification.Specifically,the study focuses on elucidating the role of TiB2 nanoparticles in augmenting the nucleation rate during the rapid directional solidification process of Ni60Cr21Fe19 alloy system.Furthermore,subsequent tensile simulations are conducted to comprehensively evaluate the anisotropic behavior of tensile properties within the solidified microstructures.The MD results reveal that the incorporation of TiB₂ nanoparticles during the rapid directional solidification of the Ni60Cr21Fe19 significantly enhances the average nucleation rate,escalating it from 1.27×1034 m-3·s-1 to 2.55×1034 m-3·s-1.Notably,within the face centered cube(FCC)structure,Ni atoms exhibit pronounced compositional segregation,and the solidified alloy maintains an exceptionally high dislocation density reaching up to 1016 m-2.Crucially,the rapid directional solidification process imparts a distinct microstructural anisotropy,leading to a notable disparity in tensile strength.Specifically,the tensile strength along the solidification direction is markedly superior to that perpendicular to it.This disparity arises from different deformation mechanisms under varying loading orientations.Tensile stress perpendicular to the solidification direction encourages the formation of smooth and organized mechanical twins.These twins act as slip planes,enhancing dislocation mobility and thereby improving stress relaxation and dispersion.Moreover,the results underscore the profound strengthening effect of TiB2 nanoparticles,particularly in enhancing the tensile strength along the rapid directional solidification direction.