| 摘要 |
A composition of matter suitable for the powder metallurgical production of wrought reinforced products comprises composite particles not over 40 microns in size, the particles containing high melting point hard refractory material and a ductile metal, the particles of one constituent being coated by the other and the hard refractory material forming 0.5-25% by volume of the total composition. For a composite powder up to 5 microns in size the refractory material preferably forms 2-15% by volume of the total composition, the metal when coated on refractory particles has a thickness 0.05-1 micron and the refractory material when coated on metal has a thickness ranging up to 0.3 micron. The refractory material may be an oxide of Ca, Be, Mg, Al, Ti, Zr, Si, Cr, Th or Ce or a silicide, boride, carbide or nitride of W, Mo, Cr, Ti, Zr, Ta, Nb or Hf. The metal may be Fe, Ni or Co or an alloy thereof with Cr. Such an alloy may contain Cr 5-30%, Fe up to 25%, Ni up to 90%, Co up to 70%, the total content of Ni and Co being at least 40%, with or without one or more of W, Mo, Nb, Ta, Ti, Al, Mn, Si, B, C and N. Refractory particles may be coated with Ni or Co by chemical deposition from solution, thermal decomposition of the carbonyls or halides or by thermal vaporization of the metal in vacuo. Metal particles may be coated with refractory oxide by first depositing the metal of the oxide by vapour deposition, or decomposition of halides and then oxidizing the metal coating. The composite particles are formed into shaped bodies by cold pressing under a pressure of 30-150 tons per square inch or hot pressing under a pressure below 30 tons per square inch and then sintering at a temperature from 1100 DEG C up to less than 5 DEG C below the incipient fusion point. Sintering may be performed in two stages of increasing temperature. The sintered body may be hot worked by extrusion, forging or swaging to reduce it in cross-section by not less than 50%, preferably 90-95%. Specification 807,093 is referred to.
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