Stress-enhanced transformations from hypothetical B2 to stable L10 and amorphous to fcc phases in Fe50Ni50 binary alloy by molecular dynamic simulations

Abstract

Molecular dynamics (MD) simulations were performed for an Fe50Ni50 (at.%) alloy with NTp ensemble to keep the number of atoms (N), temperature (T= 673 K), and pressure (p~101.325 kPa) constant under a GrujicicZhou-type MD potential from an Embedded Atom Method scheme with a cut-off distance of 1 nm. An Fe50Ni50 alloy was initially created as a hypothetical chemically-ordered B2 structure with a 12 × 12 × 12 supercell comprising 3456 atoms. Subsequently, it was annealed at 673 K, without the application of stress, and then under a uniaxial tension of ~290 MPa, and shear stresses of ~570 and ~2940 MPa. The results revealed that stress contributed to a change in the transformation scheme to the L10 phase from partially to fully of the system with a reduction of time. On the other hand, an as-quenched amorphous phase under a shear stress of ~680 MPa, transformed to a disordered fcc-derivative phase. Therefore it is clear that stresses in MD simulations play a crucial role in enhancing the atomic motion during a transformation.