Hitachi Metals, Ltd.

Hideya Yamada

Tsutomu Inui

Akira Kawakami

Shin-ichiro Yokoyama

Noriyuki Nakaoka

Shingo Kumamoto

Hironori Nakanishi

Ichiro Kishigami

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

Provided is a composite magnetic member made of a single material combining a ferromagnetic portion and a non-magnetic portion in which the ferromagnetic portion has better soft magnetism than conventional members and the non-magnetic portion has the same stable characteristic as conventional members. A method of producing the ferromagnetic portion of the member and a method of forming the non-magnetic portion are also provided. The composite magnetic member is made of an Fe&mdash;Cr&mdash;C-base alloy steel containing 0.1 to 5.0 weight % Al and has a ferromagnetic portion with a maximum magnetic permeability of not less than 400 and a non-magnetic portion with a magnetic permeability of not more than 2. In this member the number of carbides with a grain size of not less than 0.1 &mgr;m is regulated to not more than 50 in an area of 100 &mgr;m,and the proportion of the number of carbides with a grain size of not less than 1.0 &mgr;m to the number of all carbides is controlled to not less than 15%.

Composite magnetic member, method of producing ferromagnetic portion of same, and method of forming non-magnetic portion of same

Provided are a heat spreader that can reduce an increase in the thermal expansion coefficient up to high temperatures of not lower than 500.degree. C. and has an excellent thermal expansion property and an adequate heat-conductive property and a method of making the same. This heat spreader comprises high-thermal-conductivity layers made of a Cu-base metal, low-thermal-expansion layers made of an Fe--Ni-base alloy each of which layers is provided with a plurality of through holes, and thermal expansion-restraining layers of a metal with a thermal expansion coefficient .alpha. at 30-800.degree. C. of not more than 7.5.times.10.sup.-6 /.degree. C.

Heat spreader and method of making the same

Growing community of inventors

Yasugi, Japan

Hideya Yamada