Nickel-carbon phase diagram

The solvent action of nickel is shown in Fig. 12.2. When a nickel-graphite mixture is held at the temperature and pressure found in the cross-hatched area, the transformation graphite-diamond will occur. The calculated nickel-carbon phase diagram at 65 kbar is shown in Fig. 12.3. Other elemental solvents are iron and cobalt.i i However, the most common... 

The successful conversion of graphite to diamond involves crystallizing the diamond from a liquid melt. The solvent most often used is nickel metal, or alloys of nickel with other ferrous metals. The reason for this success can be seen by referring to Figure 15.7, the binary (solid + liquid) phase diagram for (nickel + carbon).u8 We note from the figure that (Ni + C) forms a simple... 

We note from the phase diagram that some nickel remains dissolved in the diamond, but the amount is small, with mole fraction of carbon > 0.9998 at the eutectic temperature. Thus, diamond of reasonably high purity is obtained. At the present time, this and similar processes are used to produce large quantities of diamonds. The crystals are usually small and find most use in industrial grinding and cutting processes. 

The main difference between the carbon and low alloy steels, shown in figures 6.1 and 6.2, was the lowering of the solidus lines by alloying elements. The liquidus temperatures were also decreased somewhat. It has not been possible to calculate the factors for the temperature depression by, for example, nickel and chromium, as the levels of other elements were not held constant in the present work. However, at the low contents present, the influence of minor changes in composition can be estimated from the binary phase diagrams. 

The X-ray diffraction patterns of hydrothermally synthesised anhydrous nickel carbonate were taken, indexed and the constants of the unit cell ascertained. The T, p phase diagram of NiC03(cr) was determined semi-quantitatively. Solid solution formation between NiCOs and MgCOs was established. In addition hellyerite, NiC03-5.5H20, and zaratite were investigated. The latter turned out not to be a single mineral, but a composite of amorphous and fibrous components. 

Kasl] Kase, T., Ternary System of Iron-Carbon-Nickel , Sci. Rep. Tohoku Imp. Univ., 1(14), 193-217 (1925) (Phase Diagram, Phase Relations, Morphology, Experimental, 5) [1925Kas2] Kase, T., On the Equilibrium Diagram of the Iron-Carbon-Nickel System , Sci. Rep. 

Soe] Soehnehen, V.E., Piwowarsky, E., About the Influence of Alloying Elements Nickel, Silicon, Aluminium and Phosphorus on the Carbon Solubility in Liquid and Solid Iron (in German), Arch. Eisenhuettenwes., 5(2), 111-121 (1931) (Experimental, Morphology, Phase Diagram, 51)... 

Paris), 6(12), 104-161 (1951) (Crys. Sfructure, ExperimentaL Magn. Prop., Review, 66) [1955Sam] Samuel, R, Finch, L.G., Rait, J.R., A Phase Diagram for I per Cent Carbon-Iron Alloys Containing up to 16 % Nickel , Nature, 175, 37-38 (1955) (ExperimentaL Phase Diagram, Phase Relations, 4)... 

War] Ward, R.G., Wright, J.A., The Solubility of Carbon in Molten Iron-Nickel Alloys , J. Iron Steel Inst., London, 194, 304-306 (1960) (Experimental, Phase Diagram, Phase Relations, Thermodyn., 10)... 

Nat] Natesan, K., Kassner, T.F., Thermodynamics of Carbon in Nickel, Iron-Nickel and Iron-Chromium-Nickel Alloys , Metall. Trans., 4, 2557-2566 (1973) (Experimental, Phase Diagram, Thermodyn., 39)... 

Ach] Achar, B.S., Miodownik, A.P., The Effect of Two y States on the Activity of Carbon in FCC Iron-Nickel-Carbon Alloys , Calphad, 1(3), 275-280 (1977) (Phase Diagram, Theory,... 

Rag] Raghavan V, C-Fe-Ni (Carbon-Iron-Nickel) , J. Phase Equilib., 15(4), 428-429 (1994) (Phase Diagram, Review, 12)... 

The phase diagram for carbon (Figure 2.2) is not clearly defined due to the possible doubtful measurements at the high pressures and temperatures involved. The triple point for graphite (Figure 2.3), where solid, liquid and gas are in equilibrium, is about 4180 K at 10.13 MPa. Carbon vaporizes about 4500 K and 1 kb (100 MPa) or, at 200 K, a pressure of 1000 kb (100 GPa) would be required. Although diamonds can be made at 10 kb (1 GPa) and 1000 K, conversion would be extremely slow and production can be effectively speeded up with catalysts such as nickel, at 100 kb (10 GPa) and 2000 K. Strictly SI does not use multiples and submultiples so N/m x 10 preferred to MN/m. But this is unwieldy and I have used multiples etc and Pa instead of N m to come into line with composite nomenclature. 

A necessary participant of the process is a set of metal-catalyst droplets. Among such metals are Fe, Co, Ni, Pd, and others, which at high metal concentration have a phase equilibrium diagram with carbon, shown in Fig. 24 for the nickel-carbon system as an example. A specific feature of the diagram is a higher solubility of carbon in liquid nickel as compared to solid nickel. 

The diagram for the system nickel-ternary eutectic at 600 °C is shown in Fig. 84 as an example. It is divided into three regions in which only one nickel phase may be present at unit activity. The boundary between the Ni" and NiO areas is the value of PCO2 at which solid NiO precipitates from a pure nickel carbonate melt. When the oxygen pressure is reduced beyond the dissociation pressure of NiO atni), nickel metal... 

Fig. 5. Metastable Fe—Ni—Cr "temary"-pliase diagram where C content is 0.1 wt % and for alloys cooled rapidly from 1000°C showing the locations of austenitic, duplex, ferritic, and martensitic stainless steels with respect to the metastable-phase boundaries. For carbon contents higher than 0.1 wt %, martensite lines occur at lower ahoy contents (43). A is duplex stainless steel, eg. Type 329, 327 B, ferritic stainless steels, eg. Type 446 C, 5 ferrite + martensite D, martensitic stainless steels, eg. Type 410 E, ferrite + martensite F, ferrite + pearlite G, high nickel ahoys, eg, ahoy 800 H,...

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