1. Field of the Invention
The present invention relates to a magnetostrictive alloy having a high coefficient of magnetostriction, and more particularly to a magnetostrictive alloy which is suitable for use as a primary element of a device designed to convert magnetic energy to mechanical energy and vice versa.
The present invention also relates to methods of producing the magnetostrictive alloy mentioned above.
2. Description of the Related Art
Magnetic materials are deformed by magnetostriction when an external magnetic field is impressed. Applying this effect, magnetic-mechanical displacement conversion devices (hereinafter referred to as "devices") have been developed. In the vibration field these devices are, magnetostriction vibrators, applicable to speakers, sonars, ultrasonic delay lines, ultrasonic processing machines, vibration-preventive and vibration-isolating mechanisms, and the like. In the mechanical application field they are used in displacement control actuators, precision positioning mechanisms, control valves, mechanical switches, micro pumps, printer heads, and the like. Furthermore, as sensors, they are also used in pressure sensors, knock sensors, sound pressure sensors, and the like. In addition, they are also applicable to devices using elastic surface waves. Thus, magnetostriction materials are extremely useful in the industrial field.
As magnetostriction materials used for these devices, Ni-base alloys, Fe-Co alloys and ferrite materials are known. Recently, rare earth-iron intermetallic compounds of the Laves type (expressed by the general expression AB.sub.2 having the cubic crystal structure MgCu.sub.2, and having a saturated magnetostriction of 1000.times.10.sup.-6 or more) have been reported (Japanese Patent Publication TOKKU-KO-SHO No. 61-33892). The compounds of the present invention have a greater absolute quantity of magnetostriction than the conventional magnetostriction materials mentioned above.
Recently the magnetostrictive alloy rods have been manufactured by the floating zone refining method (Japanese Patent Disclosure TOKKU-KAI-SHO No. 62-109946 or U.S. Pat. No. 4,609,402) and the improved type Bridgman method (Japanese Patent Disclosure TOKKU-KAI-SHO No. 63-242442 or European Open Patent No. 282059) to form a magnetostrictive alloy having a large magnetostriction. Such methods, however, form the magnetostriction alloy into parts that are relatively small in diameter, only rod shaped and at a high manufacturing cost. Such methods are, therefore, not adequate for mass production.
Moreover, to be practically useful such materials should exhibit large magnetostriction in a magnetic field as low as several kOe. In such a low magnetic field, magnetostriction alloys having satisfactory magnetostrictive characteristics consisting of the rare earth-iron system alloys have not yet been developed.
The present invention has been made in view of the circumstances described above. It is an object of the present invention to provide magnetostrictive alloys that show large magnetostriction even in a low magnetic field.
It is a further object of the present invention to provide a method of making the magnetostrictive alloys mentioned above.