High Temperature Elastic Constants of α-Fe Single Crystal Studied by Electromagnetic Acoustic Resonance

抄録

Complete set of elastic constants C_ij of α-Fe single crystal have been investigated from ambient temperature up to 893 K by electromagnetic acoustic resonance. Longitudinal component of elastic constants C₁₁ showed linear temperature behavior and the magnitude of elastic softening was approximately 13%. The remainning two shear moduli, C₄₄ and C′, however showed highly nonlinear behaviors with significant softenings of 50%. On a Blackman diagram, elastic constant ratios at high temperatures move to a limit, C₁₂/C₁₁=1 and C₄₄/C₁₁=0, where Born's two lattice instability criteria have been satisfied simultaneously. Violation of Cauchy relation is also significant upon heating.