Molecular dynamics simulation of the interactions between screw dislocation and stacking fault tetrahedron in Fe–10Ni–20Cr and Ni

Abstract

Radiation-induced defects are the significant cause of radiation damage in austenitic stainless steels. In this work, the interactions between a screw dislocation and stacking fault tetrahedrons (SFTs) are studied in Fe–10Ni–20Cr (a model alloy of austenitic stainless steel) and Ni, using molecular dynamics simulations. Four interaction processes were primarily found, including (1) partial absorption, (2) sheared, (3) bypassing, and (4) restored through double cross-slip. In Fe–10Ni–20Cr alloys, there is almost no correlation between the critical resolved shear stress (CRSS) value and SFT size, but the intersection position largely impacts the results. And the CRSS value decreases with temperature increasing in Fe–10Ni–20Cr. The occurrence of cross-slip has a significant effect on the interactions, and there exist greater CRSS value in the interactions of cross-slipping. Besides, the occurrence of the cross-slip is linked to the stacking fault energy and the distribution of solute atoms of the alloys.

Molecular dynamics study of interactions between edge dislocation and irradiation-induced defects in Fe–10Ni–20Cr alloy

“…The SFT was created by deleting an equilateral triangle vacancy layer atom on the {111} plane with a static relaxation through the LAMMPS code. [4,29] During the simulation, the NPT ensemble was used to ensure that the pressure in the pressure reaction vessel does not change after increasing the temperature of the reaction system. After the system was heated to target temperatures (300 K, 600 K, and 900 K), it was relaxed for 30 ps, the time step for the whole MD simulation is chosen to be 2 fs.…”

“…[2,3] Under irradiation, as is well known, Frank loops are common interstitial-type defects, while voids and SFTs are vacancy-type defects in face-centered cubic (FCC) crystals. [4] These irradiation-induced defects will continue to accumulate and grow, which seriously impede the movement of dislocations, thus increasing the yield stress of materials significantly. [5] Besides, the irradiation-induced defects near the dislocation slip surface disappear after interacting with dislocations, which results in the localization of the plastic deformation.…”

“…Further, the researches about the reaction of SFT with dislocation are rare, and most of them only focus on pure metal systems, e.g., Cu, Au, and Ni. [4,[22][23][24][25][26] Although the interaction between screw dislocations and SFTs was investigated in Fe-10Ni-20Cr alloys and Ni, [4] the interaction of edge dislocations with SFTs has been ignored, which is also important.…”

Formation and Anisotropic Mechanical Behavior of Stacking Fault Tetrahedron in Ni and CoCrFeNiMn High-Entropy Alloy

“…The defects, including stacking fault tetrahedrons (SFTs), voids, dislocation loops, and bubbles, would be generated in metals subjected to long-term irradiation or severe deformation (Wu et al, 2018b;Wu et al, 2018c;Zhang et al, 2018;Chen et al, 2020). These defects would affect the mechanical properties of materials, such as irradiation hardening, swelling, embrittlement, and irradiation-assisted stress corrosion cracking (Bacon et al, 2009).…”

“…Despite the rapid development of experimental technology, it is still very challenging to study the evolution of SFTs under shear stress in different directions through experiments. Molecular dynamics (MD) simulations is an effective means to investigate the formation and evolution of microstructures under irradiation (Aidhy et al, 2015;Drouet et al, 2016;Dai et al, 2017;Zhu et al, 2017;Leino et al, 2018;Ke et al, 2019) and various mechanical loading (Weng et al, 2020;Chen et al, 2021;Weng et al, 2021), and the evolution of SFTs (Wu et al, 2018b;Wu et al, 2018c;Zhang et al, 2018;Chen et al, 2020). To study the formation and aggregation of vacancies using MD simulation of irradiation requires a long time and a lot of computing resources.…”