Low Temperature Thermal Expansion of Fe₇₂Pt₂₈ Invar Alloy

Abstract

The low temperature thermal expansions of the Fe₇₂Pt₂₈ Invar alloy were measured. The thermal expansion coefficients in both ordered and disordered states are small, negative and linear in T. No appreciable difference has been detected between the two states. The magnitude of the linear negative thermal expansion coefficients is about five times as small as that of the Fe₆₆Ni₃₄ Invar alloy, which is interpreted in terms of strong ferromagnetism of Fe–Pt Invar alloys in contrast to weak ferromagnetism of Fe–Ni Invar alloys.