PURPOSE: To further improve the heat resistance of rotary twin-cathodes in a rotary twin-cathode X-ray device by using a specific distributed reinforcement type alloy as the material of the rotary twin cathodes emitting X-rays irradiates with electron beam.

CONSTITUTION: A distributed reinforcement type alloy is used as the material of rotary twin cathodes emitting X-rays when irradiated with electron beam, the combination of the host metal and dispersed grains in this distributed reinforcement type alloy is selected so that the wavelength of characteristic X-rays by the dispersed grains is not proximate to the wavelength of characteristic X-rays of the host metal. Hard and fine grains stabilized at a high temperature are dispersed and combined in the distributed reinforcement type alloy, the phase (dispersed phase) of the dispersed grains acts as the barrier against the transition shift, the dispersed phase is prevented from melting into the host metal, thus the temperature dependency of the mechanical characteristic is extremely small, and the initial mechanical characteristic can be maintained without being impaired so much even when heated to the high temperature near the melting point.