GeV ion irradiation of NiFe and NiCo: Insights from MD simulations and experiments

Abstract

Concentrated solid solution alloys have attracted rapidly increasing attention due to their potential for designing materials with high tolerance to radiation damage. To tackle the effects of chemical complexity in defect dynamics and radiation response, we present a computational study on swift heavy ion induced effects in Ni and equiatomic Ni -based alloys (Ni 50 Fe 50 , Ni 50 Co 50 ) using two-temperature molecular dynamics simulations (2T-MD). The electronic heat conductivity in the two-temperature equations is parameterized from the results of first principles electronic structure calculations. A bismuth ion (1.542 GeV) is selected and single impact simulations performed in each target. We study the heat flow in the electronic subsystem and show that alloying Ni with Co or Fe reduces the heat dissipation from the impact by the electronic subsystem. Simulation results suggest no melting or residual damage in pure Ni while a cylindrical region melts along the ion propagation path in the alloys. In Ni 50 Co 50 the damage consists of a dislocation loop structure (d=2nm) and isolated point defects, while in Ni 50 Fe 50 , a defect cluster (d=4nm) along the ion path is, in addition, formed. The simulation results are supported by atomiclevel structural and defect characterizations in bismuth-irradiated Ni and Ni 50 Fe 50 . The significance of the 2T-MD model is demonstrated by comparing the results to those

Thermal stability and irradiation response of nanocrystalline CoCrCuFeNi high-entropy alloy

“…Although radiation-induced defects and defect clusters are expected to be trapped or eliminated in these chemical or structural inhomogeneities, interactions of defects with GBs, however, can lead to GB chemical and structural changes that involve further complications and pose additional scientific questions. Substitutional solid solutions, with increasing structural and chemical complexities that are intrinsic in HEAs, cause unique site-to-site distortion and a locally disordered chemical environment, which may have a profound effect on the fundamental processes determining defect dynamics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][18][19][20][21][22]. Such extreme elemental inhomogeneities in HEAs may strongly affect microstructure evolution in nanocrystalline films under ion irradiation.…”

Effects of 3d electron configurations on helium bubble formation and void swelling in concentrated solid-solution alloys

“…Nonadiabatic energy transfer between atoms and electrons is controlled by the strength of the electron-phonon (el-ph) coupling as one of the intrinsic properties of specific alloys. [33][34][35] Dissipation of inelastic energy (deposited to electrons) interacts with elastic energy transfer processes (energy deposited simultaneously to atomic recoils), which influences the shape and size of collision cascade damage. The substantial reduction of electrical and thermal conductivities in SP-CSAs highlights the need to pay attention to the local heat dissipation.…”

“…The modification can either be direct, through changes in the mean free path, or indirect, through changes in the flow of energy from electronic subsystem to the atomic subsystem via electron-phonon coupling. [33][34][35] Clearly, varying the chemical complexity of SP-CSAs has the potential to tune the mean free path, interaction strength, and energy dissipation. Consequently, such electronic and atomic-level chemical modification affects void and bubble formation, as well as the subsequent evolution.…”

Non-Equilibrium Thermal Transport: A Review of Applications and Simulation Approaches

“…When the nuclear fuel and its coating go through an ion [41][42][43][44][45][46][47] cascade, the incident ions strike into the materials. Unlike laser irradiation, incident ions not only heat up electrons due to the electronic stopping effect, part of their kinetic energy is also transferred to the lattice which at the same time produce point defects in the structure.…”