Abstract: Restoring magnetostriction characteristics without causing fusion of rod. By performing heat treatment on a giant magnetostrictive material within the temperature range of 750 to 860° C., working distortion is removed while bleeding of an R-rich phase on a rod surface is prevented.

Abstract: A torque sensor includes a substantially tubular giant magnetostrictive member, a shaft passing through the inner bore of the giant magnetostrictive member and capable of transmitting torque to the giant magnetostrictive member, and a detection coil for detecting changes in the magnetic permeability or remnant magnetization of the giant magnetostrictive member. Torque changes of the shaft are detected as changes in the magnetic permeability or remnant magnetization of the giant magnetostrictive member, based on the deformation of the giant magnetostrictive member. The torque sensor enables a reduction in the number of components and costs, as well as detection of torque changes with high sensitivity.

Abstract: In the step of sintering a compact that is finally to be a magnetostrictive element, when the temperature in a furnace is elevated, the atmosphere in the furnace is evacuated by a vacuum pump to keep the pressure in the furnace at negative pressure in a temperature range that allows thermal decomposition of hydride present in the compact to release hydrogen gas to accelerate release of hydrogen from the compact.

Abstract: It is an object of the present invention to provide a method for producing a magnetostrictive element which can give an anisotropic magnetostrictive element from a starting material containing Sm and a transition metal element. The method produces an anisotropic magnetostrictive element by compacting the starting powder in a magnetic field to produce a compact, and sintering the compact to produce a sintered body having a composition of SmFe2. It is preferable that the starting powder is produced by mixing a first alloy for the main phase of the magnetostrictive element with a second alloy having a lower melting point than the first alloy. It is recommended that the first alloy has a larger particle size than the second alloy.

Abstract: A torque sensor includes a substantially tubular giant magnetostrictive member, a shaft passing through the inner bore of the giant magnetostrictive member and capable of transmitting torque to the giant magnetostrictive member, and a detection coil for detecting changes in the magnetic permeability or remnant magnetization of the giant magnetostrictive member. Torque changes of the shaft are detected as changes in the magnetic permeability or remnant magnetization of the giant magnetostrictive member, based on the deformation of the giant magnetostrictive member. The torque sensor enables a reduction in the number of components and costs, as well as detection of torque changes with high sensitivity.

Abstract: In the step of sintering a compact that is finally to be a magnetostrictive element, when the temperature in a furnace is elevated, the atmosphere in the furnace is evacuated by a vacuum pump to keep the pressure in the furnace at negative pressure in a temperature range that allows thermal decomposition of hydride present in the compact to release hydrogen gas to accelerate release of hydrogen from the compact.

Abstract: Restoring magnetostriction characteristics without causing fusion of rod. By performing heat treatment on a giant magnetostrictive material within the temperature range of 750 to 860° C., working distortion is removed while bleeding of an R-rich phase on a rod surface is prevented.

Abstract: Disclosed is the addition of at least two elements of Nb, V, Ta and Zr to the ternary alloy of R (rare earth)-Co-Cu for permanent magnet materials, to thereby provide the permanent magnets with increased coercive force, residual magnetization and energy product. The additional elements enable employment of such Cu and Fe contents of the alloy as less than 10% and more than 6%, respectively. These percentages were avoided in the prior art to prevent the reduction of Br and Hc, respectively.