Hitachi Metals, Ltd.

Noriyuki Nakaoka

Akira Kawakami

Tsutomu Inui

Hideya Yamada

Yoshiyuki Fujihara

Shinichiroh Yokoyama

An object of the present invention is to solve the problem in hot workability caused by Cu aggregation and provide semi-hard magnetic materials having good magnetic properties, bias materials for magnetic markers, magnetic markers and production methods of bias materials for magnetic markers. The present invention provides a semi-hard magnetic material including 2.0%&#x2266;Cu&#x2266;10.0% and 0.1%&#x2266;Nb&#x2266;5.0% by mass %, the balance being Fe and inevitable impurities, and having a microstructure in which Cu phase and an intermetallic compound of Fe and Nb are dispersed. The semi-hard magnetic material of the present invention is suitable as bias materials for magnetic markers. Furthermore, the bias materials for magnetic markers can be formed by disposing bias materials for magnetic markers mentioned above so that a bias magnetic field may be applied to a magnetostrictive element for a magnetic marker.

Semi-hard magnetic material, bias material for magnetic marker, magnetic marker and production method of bias material for magnetic marker

The invention relates to a semi-hard magnetic material having rectangular hysteresis loop and superior magnetization steepness and a method of producing a bias material preferably used for a magnetic marker. This method comprises the steps of preparing a multilayer clad material in which layers 'A' each containing Fe as the main component thereof and layers 'B' containing as the main component thereof a Cu group metal are diffusion-bonded, heating the multilayer clad material, subjecting the material to a dividing treatment, and applying cold working thereto. By this method, it becomes possible to obtain the semi-hard magnetic material having high squareness ratio and superior magnetization steepness, and to obtain the bias material for the magnetic marker.

Production method for semirigid magnetic material and semirigid material and magnetic marker using it

A bias material for magnetic markers is produced by plastic working to provide a strip form, which has a metal structure consisting of the iron-base matrix and a non-magnetic copper group metal phase in an amount of not less than a solubility limit thereof in an equilibrium state at a room temperature. The non-magnetic copper group metal phase is dispersed in the matrix so as to form a microstructural rod pattern. The bias material comprises preferably 3 to 35% wt % of a copper group metal. The magnetic marker is produced by combining the bias material and a magnetostriction element.

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Yasugi, Japan

Noriyuki Nakaoka