ANALYSIS OF SINGLE-CRYSTALLINE IRON TENSILE DEFORMATION USING APPROXIMATION NEGLECTING FLUCTUATIONS AND MOLECULAR-DYNAMICS SIMULATION

This paper describes the investigation of brittle to ductile transition in alpha-iron using an approximation in which fluctuations are neglected, and a molecular dynamics simulation. By introducing two kinds of forces, the tendency to slip or cleave is evaluated, using an approximation in which the atom position fluctuations are neglected. For ideal crystals, expanded alpha-iron single crystals tend to be more ductile than compressed ones in the case of uniform tensile deformation. Crack propagation and blunting processes are simulated in alpha-iron using a molecular dynamics approach utilizing the Johnson potential. The simulations show that expanded crystals are likely to undergo shear breakdown and that compressed ones are likely to fail due to cleavage. The results obtained from molecular dynamics simulations are found to be consistent with those obtained from the analysis that neglects fluctuations.