Cr-Based Magnetically Insensitive Invar-Type Alloys
During the past several decades, many kinds of Invar-type alloys have been discovered. However, the practical Invar-type alloys are all ferromagnetic, and applications of them are often restricted because of their ferromagnetism. Therefore, research to develop magnetically insensitive (i.e. nonferromagnetic) Invar-type alloys has recently received considerable attention. Although there are nonferromagnetic materials with low thermal expansion, such as SiO_2-TiO_2 glasses, α-Mn, rare earth metals etc., these materials have some disadvantage from the practical viewpoint. Physical properties of antiferromagnetic Cr are modified by small amounts of additional elements. In the case of Cr-Fe and Cr-Si alloys, the thermal expansion coefficient becomes very small due to the large spontaneous volume magnetostriction. Then, a number of Cr-Fe and Cr-Si-based Invar-type alloys have been obtained by means of the regulation of the thermal expansion characteristics and the Neel temperature. These Cr-based antiferromagnetic Invar-type alloys are magnetically insensitive because they are antiferromagnetic, and no trouble takes place in practical applications. The ductility of Cr-based alloys is not so good, but the workability of them is improved by addition of rare earth elements. These Cr-based Invar-type alloys simultaneously show the Elinvar characteristics. Therefore, they are expected to apply for various electromagnetic devices such as delay lines etc.
- Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy
Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy 26 299-332, 1976