Phase diagrams copper-nickel

One of the most important attributes of nickel with respect to the formation of corrosion-resistant alloys is its metallurgical compatibility with a number of other metals, such as copper, chromium, molybdenum, and iron. A survey of the binary phase diagrams for nickel and these other elements shows considerable solid solubility, and thus one can make alloys with a wide variety of composition. Nickel alloys are, in general, all austenitic alloys however, they can be subject to precipitation of intermetallic and carbide phases when aged. In some alloys designed for high-temperature service, intermetallic and carbide precipitation reactions are encouraged to improve properties. However, for corrosion applications, the precipitation of second phases usually promotes corrosion attack. The problem is rarely encountered because the alloys are supplied in the annealed condition and the service temperatures rarely approach the level required for sensitization. 

Isomorphous diagrams are those for which there is complete solubility in the solid phase the copper-nickel system (Figure 9.3a) displays this behavior. 

Tables 1 and 2, respectively, Hst the properties of manganese and its aHotropic forms. The a- and P-forms are brittle. The ductile y-form is unstable and quickly reverses to the a-form unless it is kept at low temperature. This form when quenched shows tensile strength 500 MPa (72,500 psi), yield strength 250 MPa (34,800 psi), elongation 40%, hardness 35 Rockwell C (see Hardness). The y-phase may be stabilized usiag small amounts of copper and nickel. Additional compilations of properties and phase diagrams are given ia References 1 and 2.

Phase diagrams have been measured for almost any alloy system you are likely to meet copper-nickel, copper-zinc, gold-platinum, or even water-antifreeze. Some... 

Fig. 3.6. (a) The copper-nickel diagram is a good deal simpler than the lead-tin one, largely because copper and nickel are completely soluble in one another in the solid state. (b) The copper-zinc diagram is much more involved than the lead-tin one, largely because there are extra (intermediate) phases in between the end (terminal] phases. However, it is still an assembly of single-phase and two-phase fields. 

Alloys are prepared commercially and in the laboratory by melting the active metal and aluminum in a crucible and quenching the resultant melt which is then crushed and screened to the particle size range required for a particular application. The alloy composition is very important as different phases leach quite differently leading to markedly different porosities and crystallite sizes of the active metal. Mondolfo [14] provides an excellent compilation of the binary and ternary phase diagrams for aluminum alloys including those used for the preparation of skeletal metal catalysts. Alloys of a number of compositions are available commercially for activation in the laboratory or plant. They include alloys of aluminum with nickel, copper, cobalt, chromium-nickel, molybdenum-nickel, cobalt-nickel, and iron-nickel. 

In the systems described so far, only pure solids have been involved. Many solids are capable of dissolving other materials to form solid solutions. Copper and nickel, for example, are soluble in each other in all proportions in the solid state. The phase diagram for the copper-nickel system is shown in Fig. 15.16. 

The present monograph was first written as a chapter for Volume 8 of the series Materials Sdence and Technology A Comprehensive Treatment , edited by Robert W. Cahn, Peter Haasen, and Edward J. Kramer (Volume Editor Dr. Karl Heinz Matucha). Its aim is to give an overview of intermetallics, which is both detailed and comprehensive and which includes the fundamentals as well as applications. The result is an extended, critical review of the whole field of intermetallics with an emphasis on those intermetallic phases which have already been applied as functional or structural materials or which are currently the subject of materials developments. A historical introduction and a discussion of the relationship between atomic bonding, crystal structure, phase stability and properties is followed by a discussion of the major classes of intermetallics. The titanium aluminides, nickel aluminides, iron aluminides, copper phases, A15 phases. Laves phases, beryllides, rare earth phases, and siliddes are reviewed. In particular, the crystal structures, phase diagrams, and physical properties as well as the mechanical and corrosion behavior are treated. The state of developments as well as prospects and problems are discussed in view of present and future applications. The publisher has decided to publish the review as a separate monograph in order to make it accessible to a wider audience. 

The simplest form of two-component phase diagram is exhibited by components that are very similar in chemical and physical properties. The nickel-copper... 

At the bottom of the diagram, corresponding to the lowest temperatures, another homogeneous phase, a sohd, called the a phase, is found. Just as in the hquid phase, the copper and nickel atoms are distributed at random and, by analogy, such a material is called a sohd solution. Because the sohd solution exists from pure copper to pure nickel it is called a complete sohd solution. (The physical and chemical factors underlying sohd solution formation are described in Section 6.1.3.)... 

Figure 4.8 Part of the nickel-copper (Ni u) phase diagram not to scale...

An equilibrium sample of a copper-nickel (Cu-Ni) alloy with a composition of 65 wt% nickel is prepared. With reference to the Cu-Ni phase diagram shown in Figures 4.6 and 4.8 ... 

One of the most important phase transitions occurs when a liquid transforms into a solid. A great deal of information concerning the microstmcture of the solid can be obtained from a consideration of the phase diagram of the material, even though phase diagrams refer to equilibrium conditions and solidification is rarely carried out so slowly as to be an equilibrium process. For example, consider the solidification of a simple nickel-copper alloy, from the point of view of the phase diagram, reproduced in Figure 8.2. 

Koe] Koester, W., Dannoehl, W., The Copper-Iron-Nickel System (in German), Z. Metallkd., 27, 220-226 (1935) (Experimental, Phase Diagram, 17)... 

Bra] Bradley, A.J., Cox, W.F., Goldschmidt, H.J., An X-Ray Study of the Iron-Copper-Nickel Equilibrium Diagram at Various Temperatures , J. Inst. Met., 67, 189-201 (1941) (Crys. Stracture, Experimental, Phase Diagram, Phase Relations, 14)... 

Mos] Moser, Z., Zakulski, W., Spencer, R, Hack, K., Thermodynamic Investigations of Solid Copper-Nickel and Iron-Nickel Alloys and Calculation of the Solid State Miscibility Gap in the Copper-Iron-Nickel System , Calphad, 9(3), 257-269 (1985) (Phase Diagram, Phase Relations, Experimental, Thermodyn., Calculation, 44)... 

Gup] Gupta, K.P., Rajendraprasad, S.B., Jena, A. K., The Copper-Iron-Nickel System , J. Alloy Phase Diagrams, 3(2), 116-127 (1987) (Crys. Stracture, Phase Diagram, Phase Relations, Review, 40)... 

Gup] Gupta, K.P., The Cu-Fe-Ni (Copper-Iron-Nickel) System in Phase Diagram of Ternary Nickel Alloys , Indian Inst. Metals, Calcutta, (1), 290-315 (1990) (Review, Crys. Stractue, Phase Diagrams, Phase Relations, 38)... 

Leb] Lebrun, N., Cu-Ni (Copper-Nickel) , MSIT Binary Evaluation Program, in MSIT Workplace, Effenberg, G. (Ed.), MSI, Materials Science International Services GmbH, Stuttgart Document ID 20.14832.1.20, (2002) (Crys. Stracture, Phase Diagram, Phase Relations, Assessment,, , 51)... 

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