On the preparation of copper-nickel alloys by sulfide-oxide reactions
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On the Preparation of Copper-Nickel Alloys by Sulfide-Oxide Reactions SHAMSUDDIN AND P. M. PRASAD In this communication a new method has been presented for preparation of copper-nickel alloys per alloy powders by sulfide-oxide interaction. In g e n e r a l a sulfide-oxide reaction for alloy preparation may be represented as: M S ( s , 1 ) + 2 M ' O ( s ) ~ ( M - 2 M ' ) ( s , 1)+SO2(g) Fig. 3--16 pct Pd-Pb at a magnification of 600 times. Pb is dark, Pb~Pd is light.
Fig. 4--24 pct Pd-Pb at a magnification of 500 times. Pb2Pd is dark, Pb-Pd is light. ple. This anomaly, however, was not investigated further. The eutectic composition and temperature reported here are within R u e r ' s e r r o r but are considered more accurate because of the more reliable method used. The liquidus values show g r e a t e r difference from Ruer's; Ruer may have e r r e d because of undercooling of the alloys with higher palladium content, the inaccuracy of his temperature measurement, and possible systematic e r r o r . The author would like t o thank J. Corso for preparing the alloys, A. Daley for making the photomicrographs, N. G. Koopman for helpful discussions, and E. Brandis for translating R u e r ' s paper. 186 VOLUME8B, MARCH 1977
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where MS and M'O represent the sulfide and oxide of metals M and M', respectively. Preparation of alloys by such reactions has the potential advantage of cutting down the s t e p s of melting and casting and yields alloys per alloy powders directly. Since the reaction takes place in situ on the microscopic scale, the resultant product is expected t o be free from segregation of the individual metals. The concept of sulfide-oxide interaction as a means of preparing alloys has not received adequate attention of metallurgists. Free energy changes of sulfide-oxide reactions relevant to the preparation of copper-nickel alloys, shown in Table I, indicate that all these r e a c tions a r e thermodynamically feasible under standard conditions at temperatures r a n g i n g from 876 t o 1763 K. However, under a dynamic vacuum of 1.332 P a these reactions become thermodynamically feasible at much lower temperatures viz 486 to 1043 K. Although, T a f e l and Klewata4 have reported the formation of a Cu-Ni alloy by the Cu2S-NiO reaction four decades ago and Ni3S2-Cu20 reaction is believed to take place in the blowing of nickel matte,S systematic studies have been conducted only recently on the Cu2S-NiO (Ref. 6), Ni3S2-Cu20 (Ref. 7) and Co4S3-NiO (Ref. 8) reactions leading to the formation of respective alloys of specific compositions. In the present investigation conditions for the preparation of Cu-Ni alloys per alloy powders (by reaction between the concerned sulfide-oxide mixtures) of the entire composition r a n g e have been standardized and the resultant product alloys were assessed for t h e i r properties. Materials and Experimental Procedure. Ni3S2 required for the investigation was prepared by t h e r m a l decomposition of freshly precipitated nickel sulfide as described by P r a s a d and J e n
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