Lattice dynamics in austenitic stainless steels Fe–18Cr–12Ni–2Mo and Fe–18Cr–16Ni–10Mn

Abstract

Phonon dispersion curves of austenitic stainless steels Fe–18Cr–16Ni–10Mn and Fe–18Cr–12Ni–2Mo have been measured by triple-axis neutron spectroscopy. The data were analysed using Born–von Karman interactions as well as calculations including the contribution of conduction electrons on the lattice dynamics. An appropriate description of the experimental data was obtained by taking into account two-neighbour shells plus the contribution of the electron gas. The elastic constants and moduli obtained are close to reported results by ultrasonic studies on polycrystalline samples. The phonon densities of states in both systems calculated from the dispersion curves agree well with results obtained by time-of-flight neutron spectroscopy on polycrystalline samples. The Debye temperature Θ(T) shows a minimum around 40 K, similar to copper and nickel.