Metal phase diagrams

In addition to all the metallic phase diagrams, a series of volumes devoted to ceramic systems have been published since 1964 by the American Ceramic Society and is still continuing. The original title was Phase Diagrams for Ceramists, now it is named Phase Equilibria Diagrams. Some 25,000 diagrams, binary and ternary mostly, have been published to date. There is no compilation for polymeric systems, since little attention has been devoted to phase diagrams in this field up to now. 

L. Kaufman and H. Bernstein, Computer calculations of refractory metal phase diagrams. In Phase Diagrams, Materials Science and Technology, ed. A. M. Alper, New York, Academic Press, 1970, vol. 1. 

Brewer, L., 1963, Prediction of High Temperature Metallic Phase Diagrams UC RL10701, UC-25 Metals, Ceramics and Materials. 

C. Lundin. Rare Earth Metal Phase Diagrams, Chicago, 1959. 

Alloys. Many Ge alloys have been prepared and studied. Most have been made by melting Ge with another metal, much as germanides are made. Collections of binary phase diagrams and comments about many Ge alloys are available (25—28). 

Fig. 1. Piessuie—volume—tempeiatuie phase diagram of plutonium metal (35). To convert MPa to atm, multiply by 9.9.

Fig. 9. The plutonium—oxygen phase diagram where L = Hquid a, P, y, 5, and S are metal phases and the dashed lines represent uncertain phase...

T. Massalski, ed.. Binary Mlloy Phase Diagrams, Vol. 1, American Society for Metals, Metals Park, Ohio, 1986. 

Sodium is miscible with many metals in liquid phase and forms alloys or compounds. Important examples ate hsted in Table 9 phase diagrams ate available... 

References 37 and 167 present phase diagrams of sodium with other metals. 

Phosphides. Zirconium forms several phosphides ZrP [39318-19-9] 2 [ 12037-80-8] and ZrP g [12066-61 -4]-, they are part of the Zr—P phase diagram (137). The solubiUty of phosphoms in zirconium metal is low, ca 50 ppm, and at higher concentrations it collects as separate globules at the metal grain boundaries. Analysis indicates that this material is Zr P. 

AUoy Phase Diagrams," Vol. 3, Metals Elandhook, 10th ed., ASM International, Materials Park, Ohio, 1992. 

These data underline the phase diagrams for tire pairs of elements which are in contact in microchips, where Pd-Si and Pt-Si form stable inter-metallic compounds, and An-Si forms a eutectic system. 

To make martensite in pure iron it has to be cooled very fast at about 10 °C s h Metals can only be cooled at such large rates if they are in the form of thin foils. How, then, can martensite be made in sizeable pieces of 0.8% carbon steel As we saw in the "Teaching Yourself Phase Diagrams" course, a 0.8% carbon steel is a "eutectoid" steel when it is cooled relatively slowly it transforms by diffusion into pearlite (the eutectoid mixture of a + FejC). The eutectoid reaction can only start when the steel has been cooled below 723°C. The nose of the C-curve occurs at = 525°C (Fig. 8.11), about 175°C lower than the nose temperature of perhaps 700°C for pure iron (Fig. 8.5). Diffusion is much slower at 525°C than it is at 700°C. As a result, a cooling rate of 200°C s misses the nose of the 1% curve and produces martensite. 

Smithells Metals Reference Book, 7th edition, Butterworth-Heinemann, 1992 (for data on uses and compositions of steels, and iron-based phase diagrams). 

Phase diagrams are important. Whenever materials engineers have to report on the properties of a metallic alloy, or a ceramic, the first thing they do is reach for the phase diagram. It tells them what, at equilibrium, the structure of the alloy or ceramic is. The real structure may not be the equilibrium one, but equilibrium structure gives a base line from which other (non-equilibrium) structures can be inferred. 

Figure A1.27 shows the unusual silver-strontium phase diagram. It has four inter-metallic compounds. Note that it is just five simple phase diagrams, like the Pb-Sn diagram, stuck together. The first is the Ag-SrAgj diagram, the second is the SrAgj-Sr.Agj diagram, and so on. Each has a eutectic. You can always dissect complicated diagrams in this way.

Vanadium-Sodium Compounds Most Corrosive. Physical property data for vanadates, phase diagrams, laboratory experiments, and numerous field investigations have shown that the sodium vanadates are the lowest melting compounds and are the most corrosive to metals and refractories. These compounds are thought to form by either the vapor phase reaction of NaCI and V2O5 or by the combination of fine droplets of these materials upon the cooler parts of combustion equipment. 

The polymorphism of certain metals, iron the most important, was after centuries of study perceived to be the key to the hardening of steel. In the process of studying iron polymorphism, several decades were devoted to a red herring, as it proved this was the P-iron controversy. P-iron was for a long time regarded as a phase distinct from at-iron (Smith 1965) but eventually found to be merely the ferromagnetic form of ot-iron thus the supposed transition from P to a-iron was simply the Curie temperature, p-iron has disappeared from the iron-carbon phase diagram and all transformations are between a and y. 

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