Nitrogen Effect on Lattice Dynamics of FCC Fe-Cr-Mn (Ni) Austenitic Alloys

摘要

Nitrogen effect on the crystal structure and vibrational frequency distribution of the Fe-18Cr-19Mn-N alloy was studied with neutron scattering method. The neutron diffraction measurements show that these alloys are the FCC solid solutions in the nitrogen content range from 0.38 to 0.93 wt.% and the nitrogen atoms cause the lattice dilation. The nitrogen vibrational frequency decrease was observed as a function of the lattice parameter. This effect is in agreement with Gruneizen equation estimations. The metal atom frequencies depend only slightly on the nitrogen content. Lattice dynamics calculations show that effect of lattice dilation on Me-Me bonding is balanced by the additional Me-N bonds. From the measured phonon dispersion curves of Fe-18Cr-10Mn-15Ni interatomic Me - Me force constants are derived.