Invar- and Elinvar-Type Amorphous Fe-Cr-B Alloys with High Corrosion Resistance

Amorphous (Fe_Cr_x)_B_ alloys (x=0～0.15) were prepared from the melts by using a single roller quenching technique, and their Invar and Elinvar characteristics and corrosion resistance were investigated. With an increase in chromium content, the Curie temperature and the saturation magnetic moment per metal atom decreased monotonically, while the crystallization temperature increased gradually. The thermal expansion coefficient a around room temperature became slightly larger with increasing the chromium content. Nevertheless, these amorphous alloys exhibited excellent Invar characteristics below the Curie temperature. The value of Young\u27s modulus increased remarkably by applying relatively low magnetic fields, and then saturated at the field of about 1000 Oe showing a large ΔE effect. Its value as well as a longitudinal linear magnetostriction became smaller with an increase in chromium content. The temperature coefficient of Young\u27s modulus e changed from positive value to negative one, and the temperature range showing the Elinvar characteristics became narrower with chromium content. The temperature coefficient of delay time determined from the values of a and e was very small. The corrosion resistance of these alloys was extremely improved by addition of chromium