Abstract
The flexural and torsional resonance frequencies were measured with an electrostatic driving method in vacuum and a magnetic field of H=1200 Oe for the same specimens of Fe-Ni (fcc) alloys.
The results obtained are as follows:
(1) Young’s medulus, shear modulus and compressibility in a paramagnetic state, Ep, Gp and κp, were separated from the experimental values in a ferromagnetic state respectively. Ep, Gp and κp show anomalies; The former two show a maximum and the latter a minimum in the Invar region.
The results may suggest that there exists an anomaly in the interatomic binding force of the Invar alloys.
(2) In the Invar region, the temperature coefficient of Young’s modulus, (dE⁄dT)⁄E, becomes the highest and the thermal expansion coefficient the lowest.
(3) The Elinvar property (that is, (dE⁄dT)⁄E=0) appears at 44%Ni.
