Phase transformation series

Lysne, P.C., Graham, R.A., Bartel, L.C., and Samara, G.A., Solid State Research and Application Series, VII. Shock Wave-Induced Phase Transformations A Review of the Field, Sandia Laboratories Technical Memorandum No. SC-TM-710907, Albuquerque, NM, 64 pp., December 1971. 

In 1964, two competing series of slender volumes appeared one, the Macmillan Series in Materials Science , came from Northwestern Morris Fine wrote a fine account of Phase Transformations in Comlen.ted Systems, accompanied by Marvin Wayman s Introduction to the Crystallography of Martensite Transformations and by Elementary Dislocation Theory, written by Johannes and Julia Weertman. The second series, edited at MIT by John Wulff, was entitled The Structure and Properties of Materials , and included slim volumes on Structure, Thermodynamics of Structure, Mechanical Behaviour and Electronic Properties. 

Staunton, B. Ginatonpo, P.E.A. Turchi and M. Sluiter, in Statics and Dynamics of Alloy Phase Transformations , PE.A. Turchi and A. Gonis eds., NATO-ASI series B, vol. 319.Plenum. New York, USA (1994) and references therein. 

A.K. Ardell, Mechanisms of Phase Transformations in Crystalline Solids, Inst. Metals, Monograph and Report Series, No. 33, 1969, p. 111. 

Miodownik, A. P. (1994) in Statics and Dynamics of Alloy Phase Transformations, ed. Turchi, P. and Gonis, A. (NATO ASI Series B Physics Vol. 319). (Plenum Press, New York), p. 45. 

Figure 17.1 shows the molar free energy, F, as a function of temperature for a pure, or stoichiometric, material at fixed volume. The material has a first-order phase transformation at the temperature where the molar free energies cross. The equilibrium free energy is a function of temperature only. The corresponding order parameter, , which is also a function of T as illustrated in Fig. 17.1b, is a subsidiary parameter introduced by the series expansion... 

Useful insights into the kinetics of a phase transformation that proceeds by nucle-ation and growth can be obtained by observing the fraction transformed, , under isothermal conditions at a series of different temperatures. This is usually done by undercooling rapidly to a fixed temperature and then observing the resulting isothermal transformation. The kinetics generally follows the typical C-shaped behavior described in Exercise 18.4. If a series of such curves is obtained at different temperatures, the time required to achieve, for example, ( = 0.01, 0.50, and... 

There is a small thermal hysteresis of the transition temperature, which depends on many parameters such as the rate of temperature change, mechanical stresses or crystal imperfections. From a crystal chemical view, the Ba-O framework evokes an interstitial for the central Ti4+ ion which is larger than the actual size of the Ti4+ ion. As a result, the serie of phase transformations takes place to reduce the Ti cavity size. Certainly, the radii of the ions involved impact the propensity for forming ferroelectric phases thus both PbTi03 and BaTi03 have ferroelectric phases, while CaTi03 and SrTi03 do not [5]. 

On the top of the chamber there is a cylindrical extension C which is cooled in order to effect condensation of mercury vapour. Six iron anodes A (there may be twelve or even eighteen of them) are suspended from ring R which covers the top of the chamber. Current for the rectifier is supplied by a three-phase transformer the secondary windings of which have their middles connected in a neutral point in this way the secondary windings have six ends connected to six anodes A by choking coils D in series. 

While in volumes 180 and 181 of this series several basic aspects of morphology, inter-phase structure and disorder were addressed, in the present volume, molecular interactions, modeling, phase transformation and crystallization kinetics are considered (see the subject index including keywords from volumes 180 and 181 at the end of the book). Needless to say, in spite of substantial success over 60 years or more we are still far from having a complete and unambiguous picture of polymer crystallization. We firmly believe that a fruitful approach to such a complex problem requires one to give way to many different and sometimes conflicting viewpoints, as we have attempted to do in these volumes. We do hope that they are not only a time-capsule left for... 

Certain subvalent, fourth-group compounds undergo single or a series of first-order phase transformations at increasing temperatures from their expected distorted phases to give successively more symmetrical structures ... 

Interfacial Aspects of Phase Transformations, Nato Advanced Studies, Institute Series. Series C, Vol. 87 (1982), B. Mutaftchiev, Ed., D. Reidel Publ. Cy. (Dordrecht, the Netherlands). (Surface structure, adsorption and heterogeneous nucleation.)... 

At lower temperatures, the a phase transforms through a disorder-order process into a series of ordered, fluorite-related phases which can be described with the generic formula CenO n jm- These mixed-valent compounds have compositions between CeO[ 7,4 (Ce70,2. n=7, m=I) and Ce02. The seemingly continuous variation of X at low temperatures is due to the co-existence of two phases with different stoichiometries (n, n-t D. Pure Ce 02 .2mi in contrast, exists only in a narrow composition range. 

An important class of phase transformations occurring in solids, particularly metallic alloys, are termed martensitic transformations. These solid-solid transformations involve no change of composition or atomic diffusion, but merely a local displacive change which can be usefully studied by NMR since a local atomic-scale rearrangement is involved. A series of papers from Rubini et al. has shown that the NMR spectra of metals can be used to observe and quantify the degree of martensitic transformations, since there... 

Sample preparation and data collection. In order to study the phase transformation in a sample close to the Ca2MgSi207 endmember, the minimum amount of enriched Te required to obtain an adequate signal must be calculated. First, the optimum thickness for 90% Fe enrichment was determined using Long et al. (1983) for a series of Fe-doped akermanites, Ca2FejcMgi.jcSi207. The results are listed in Table Al in terms of the dimensionless thickness (Eq. 12, this Chapter), and show that addition of 0.005 Fe atoms p.fu. would be sufficient to obtain an adequate signal for conventional transmission measurements (a dimensionless thickness of 2.6 corresponds to an... 

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