Abstract: In accordance with an embodiment, a flywheel includes a rotary shaft which is rotatably provided to the flywheel, a rotor which is fixed to the rotary shaft and rotatable with the rotary shaft, and an unrotatable stator arranged so as to face the rotor. The rotor includes first permanent magnets provided on a first surface facing the stator. The stator includes second permanent magnets which are provided on a second surface facing the rotor in correspondence with the first permanent magnets respectively and have the same polarity as that of the first permanent magnets.

Abstract: In accordance with an embodiment, a flywheel includes a rotary shaft which is rotatably provided to the flywheel, a rotor which is fixed to the rotary shaft and rotatable with the rotary shaft, and an unrotatable stator arranged so as to face the rotor. The rotor includes first permanent magnets provided on a first surface facing the stator. The stator includes second permanent magnets which are provided on a second surface facing the rotor in correspondence with the first permanent magnets respectively and have the same polarity as that of the first permanent magnets.

Abstract: A TiAl intermetallic compound source and a boride which is less stable than TiB.sub.2 are mixed and melted, followed by solidification to form a TiB.sub.2 -dispersed TiAl-based composite material in which the TiB.sub.2 is contained in an amount of 0.3 to 10% by volume. In this process, the dispersed TiB.sub.2 particles become very fine, so that the hardness as well as the elongation and bending strength of the TiAl material are improved by the finely dispersed TiB.sub.2 particles.