T. Sugano et al., PRESSURE AND TEMPERATURE REGION OF DIAMOND FORMATION IN SYSTEMS GRAPHITE AND FE CONTAINING ALLOY, DIAMOND AND RELATED MATERIALS, 5(1), 1996, pp. 29-33
The pressure and temperature region of diamond formation was determine
d using Fe50wt.%-Co50wt.% and Fe66wt.%-Ni34wt.% (invar) alloys as solv
ents of carbon. Pressure and temperature values were estimated based o
n the minimum pressure and temperature conditions of diamond formation
in the pure Ni-carbon system (5.4 GPa and 1384 degrees C). In the Fe-
Co-C system, it was found that the nucleation density of diamond was v
ery small between 1190 degrees C and 1310 degrees C, but the density a
nd particle size increased markedly at 1310 degrees C in the pressure
range 5.6-6.0 GPa. Although a minimum temperature of diamond formation
was detected at 1190 degrees C at 6 GPa in the Fe-Co-C system, the re
gion of no diamond formation was observed at a lower pressure, with th
e nucleation barrier being near the minimum pressure and temperature c
ondition. The region of diamond formation in the system Fe-Ni-C was bo
unded by the equilibrium line and the estimated eutectic line of the s
ystem. The minimum temperature of diamond formation was detected at ab
out 1280 degrees C at 5.2 GPa. The P-T regions of diamond formation fo
r both the Fe-Co-C and Fe-Ni-C systems are discussed based on the stab
ility of carbide in the solvents.