| 摘要 |
The invention relates to a process for affecting grain growth in the production of metal powder from the metals W, Mo, Ta, Nb or Re or from alloys comprising one or several of these metals, by reduction in a gas phase of the metal halides by means of hydrogen gas. The reduction may be carried out in one or several steps so that partially or completely reduced metal powder is obtained. If there is partially reduced metal powder, this powder is exposed to at least one additional treatment consisting of the mechanical decomposition of the powder and/or heat treatment at a temperature of 400 DEG -1,200 DEG C., preferably 700 DEG -1,100 DEG C. in an atmosphere containing some form of halogen. If there is a completely reduced metal powder, this powder is exposed to at least one additional treatment consisting of either a heat treatment at a temperature of 400 DEG -1,200 DEG C., preferably 700 DEG -1,100 DEG C. in an atmosphere containing some form of halogen or the mechanical decomposition of the powder followed by said heat treatment. |
