Solidus

The solidus (/) is used in names of formal addition compounds to separate the arabic numerals which indicate the proportions of individual constituents in the compound. 

BiCl3-3PCl5 bismuth trichloride—phosphorus pentachloride (1/3) 

Summarizing the definitions, one can say that, from the common point of view, the solubility (or solubility limits) and equilibrium compositions after the transition in bulk material coincide [63, 83, 84]. They are given by solidus and liquidus. In nanosystems, this is far from being true. Thus, the notions solidus and liquidus have to be reexamined when dealing with nanoparticles. 

We want to outline here the definition of solubility diagram and separate it from the definition of phase diagram which is now transformed into the nanophase diagram. Strictly speaking, the phase diagram is split, so the definitions should be split as well [81]. 

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Uquidus curve The freezing point of a molten mixture of substances varies with the composition of the mixture. If the freezing points are plotted as a function of the composition, the line joining the points is called a liquidus curve. Such mixtures usually freeze over a range of temperature. If the temperature at which the last traces of liquid just solidify (assuming that sufficient time has been allowed for equilibrium to be established) are plotted against composition the resulting line is called a solidus curve. 

The liquidus consists of the curves AC, CDE and EB the solidus comprises the horizontal hnes FCG and IlEJ as well as the vertical... 

The names of addition compounds are formed by connecting the names of individual compounds by a dash (—) and indicating the numbers of molecules in the name by Arabic numerals separated by the solidus (diagonal slash). All molecules are cited in order of increasing number those having the same number are cited in alphabetic order. However, boron compounds and water are always cited last and in that order. 

Fig. 2. Typical binary phase diagram for host and impurity, showing a constant distribution coefficient if impurity content is low. L = liquid composition after some solidification, a = B and small amount of A, /5 = A and small amount of B, = liquidus, and = solidus.

C, is the concentration of impurity or minor component in the solid phase, and Cf is the impurity concentration in the hquid phase. The distribution coefficient generally varies with composition. The value of k is greater than I when the solute raises the melting point and less than I when the melting point is depressed. In the regions near pure A or B the hquidus and solidus hues become linear i.e., the distribution coefficient becomes constant. This is the basis for the common assumption of constant k in many mathematical treatments of fractional solidification in which ultrapure materials are obtained. 

Fig. 4.5. Schematic of top left corner of the "silicon-impurity" phase diagram. To make things simple, we assume that the liquidus and solidus lines ore straight. The impurity concentration in the solid is then always less than that in the liquid by the factor k (called the distribution coefficient).

DEF. The phase boundary which limits the bottom of the liquid field is called the liquidus line. The other boundary of the two-phase liquid-solid field is called the solidus line. 

From 245°C to 183°C. The liquidus is reached at 245°C, and solid (a lead-rich solid solution) first appears. The composition of the liquid moves along the liquidus line, that of the solid along the solidus line. This regime ends when the temperature reaches 183°C. Note that the alloy composition in weight % (64) is roughly half way between that of the solid (81 wt%) and liquid (38 wt%) so the alloy is about half liquid, half solid, by weight. 

If an 80 at% Pb alloy is cooled, the first solid appears at 305°C, and is primary (Pb) with a composition of about 90% Pb (see Fig. A1.35). From 305 to 255°C the amount of primary (Pb) increases, and its composition, which (at equilibrium) follows the solidus line, changes it becomes richer in tin. This means that lead must diffuse out of the solid (Pb), and tin must diffuse in. 

The phase diagram describes the equilibrium constitution of the alloy - the one given by very slow cooling. In the last example all the liquid should have solidified at the point marked 2 on Fig. A 1.35, when all the solid has moved to the composition Xp = 80% and the temperature is 255°C. Rapid cooling prevents this the solid has not had time to move to a composition Xpp = 80%. Instead, it has an average composition about half-way between that of the first solid to appear (Xpp = 90%) and the last (Xpp = 80%), that is, an average composition of about Xpp = 85%. This "rapid cooling" solidus lies to... 

For the purpose of discussion. Table 2 summarizes HSRS data obtained from a number of Al alloys and composites. It was first noted by Nieh et al [5] that the optimum temperature for high strain rate superplasticity in an alloy is either above or close to the solidus temperature. This led them to suggest that the presence of a liquid phase might have contributed to the observed HSRS. 

Fig. 5 Elongation-to-failure as a function of testing temperature for MA materials. /The left and right arrows on each curve indicate the incipient melting point and solidus temperature, respectively.

Because the appearance of a superlattice is usually well characterized qualitatively in terms of an interaction parameter w which has nothing to do, in the usual treatments, with the melting of the parent solid solution, one does not expect to find a simple relationship between the critical temperature for disordering of the superlattice, and Ts, the solidus temperature of the corresponding solid... 

Measurements of solidus and liquidus temperatures need to be established. 

The solidus, the liquidus, the oxygen-potential model for the solid Pu/0 system, and the oxygen-potential model for the liquid Pu/0 system each depend upon the temperature and composition. Because the oxygen-potential model has a greater effect on the vapor pressure and composition at high temperature than do the solidus and liquidus, we have fixed the functional forms and the parameter values for the oxygen-potential model. We choose the IAEA solidus (32) and determine the liquidus that is consistent with it and with the two parts of the oxygen-potential model. The calculated liquidus, which is based on the liquid model parameters, is very close to the IAEA liquidus (33). 

International Atomic Energy Agency, solidus and liquidus for Pu02... 

We have found it possible to formulate a simple treatment of the lead-thallium alloys that accounts satisfactorily for the existence of a maximum in melting-point displaced from the composition PbTls of the ordered structure, and that also accounts in a reasonably satisfactory way for the shapes of the liquidus and solidus curves throughout the range 0—75 atomic percent thallium (Fig. 1). The maximum in these curves occurs at a composition near that for a compound Pb2Tl3 or a compound PbTl2. If either of these compounds existed, it would have to be considered as forming solid solutions with lead and with thallium. The data, however, give no evidence for the existence of such compounds. 

Fig. 7. The free-energy curves and the derivation of the liquidus and solidus curves.

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