Metal treatment – Compositions – Heat treating
Patent
1976-04-13
1977-06-21
Stallard, W.
Metal treatment
Compositions
Heat treating
75223, 75224, 148 31, B22F 104
Patent
active
040309460
ABSTRACT:
The process prevents prior powder particle boundary delineation by providing one or more surfactant elements which prevent nucleation of carbides at the particle surfaces with the result that carbide precipitation occurs within the powder particles rather than predominantly at the particle surfaces. In one embodiment, a small but effective amount of one or more surfactants is added to prealloyed powder before the powder is enclosed and densified at elevated temperature. In another embodiment, the surfactant is added to the melt of the prealloyed powder prior to atomization. The surfactant should be capable of forming a vapor under the conditions of hot densification, should be a strong oxide and/or sulfide former, must be a weak carbide former, should form oxides and/or sulfides which will not nucleate carbides of other elements, and which, if present in the article made from the powder, will not objectionably affect the desired properties. Useful surfactants include magnesium, barium, calcium, cerium, lanthanum, lithium, neodymium, praseodymium, yttrium, and misch metal.
REFERENCES:
patent: 3653982 (1972-04-01), Prill
patent: 3720551 (1973-03-01), Allen
patent: 3802938 (1974-04-01), Collins et al.
patent: 3884676 (1975-05-01), Nadkarni et al.
patent: 3890816 (1975-06-01), Allen et al.
patent: 3953205 (1976-04-01), Cox et al.
Metals Engineering Quarterly, Nov. 1974, pp. 47-49.
Muzyka Donald R.
Walley Robert F.
Carpenter Technology Corporation
Jay Edgar N.
Stallard W.
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