Magnetovolume Effects and Invar Characters of (Zr1-xNbx)Fe2

Thermal expansions of (Zr_1-xNb_x)Fe₂ intermetallic compounds with 0≤x≤0.35 were measured from 4.2 to 800 K. A remarkable thermal expansion anomaly was observed just below the Curie temperature. This anomaly is ascribed to a large spontaneous volume magnetostriction whose magnitude is almost constant up to x{=}0.3. Because of a relatively low Curie temperature, the compound with x{=}0.3 shows a similar thermal expansion to that of the Invar alloy. The forced volume magnetostriction at room temperature is also as large as that of the Invar alloy. The interrelations between the magnetovolume effects are examined on the basis of a phenomenological theory. The origin of the large magnetovolume effects and the Invar characters of the system are discussed.