Liquidus phase projections

Wanl] compiled a fliermodynamic database of the Cu-Fe-X (X Al, Co, Cr, Mn, Mo, Ni, Nb, V) systems by the CALPHAD method. According to [2004Wanl], on the basis of this database much information concerning stable and metastable phase equilibria, isothermal and vertical sections, molar fractions of constituent phases, liquidus surface projection, etc., could be predicted. 

The liquidus surface projection of the partial Fe-Fc3C-WC-W system consfructed by [1968Jel] contradicts to the constitution of die currently accepted binary systems. In particular, die W2C phase is presented by one modification the Fc3C phase is shown as stable invariant equilibrium widi the participation of the liquid, (6Fe) and the p phase in die Fe-W system is presented as the eutectic one taking place at 1520°C, and the corresponding invariant point is shifted towards the timgsten side. Stracture formation of die C-Fe-W alloys... 

Mie] Equilibrium of liquid, ferrite and austenite was assessed using ThermoCalc package. For the phases the thermodynamic parameters were optimized and tire liquidus curve projection was presented... 

Figure 10.25 shows the liquidus projection for the Al-Fe-Mn system which is characterised by a substantial extension of the Al Mn phase into the ternary and... 

Polythermal projections of the liquidus discussed in section 4.3.2. do not provide information on the compositions of solid phases if solid solutions or non-stoichiometric compounds are formed at equilibrium. For providing this information, the method of isothermal section is particularly useful. The following figure represents a simple ternary eutectic system with terminal solid solutions formed. 

Consider first the Al-Fe-Ni system. Generally, the equilibrium phase diagram is known to be helpful in analysing the process of intermetallic layer formation. Projection of the liquidus surface on the concentration triangle and distribution of the phase fields in the solid state for Al-rich Al-Fe-Ni alloys are shown in Fig. 5.15. 

Figure 2.3 (a) Isometric projection (solid diagram) for a hypothetical ternary system (b) isotherm (horizontal section) (c) binary-phase subset (d) liquidus surface. 

Figure 3. Al-Cu-Zn phase diagram, liquidus projection (Ref. 14) (+) alloys investigated by Friedrich et al. [26] ( ) alloys investigated by Bridgewater et al. [27].

The general methodology used can be described as follows. The user sets up the problem by specifying the type of calculation to be made (e.g. isotherm, isopleth, or liquidus projection) and then selects the database from which the thermodynamic data will be imported. The system components are defined, as well as the phases that are present and the temperature, pressure, and composition ranges over which to make the equilibrium calculations. All of this is accomplished via the user interface. 

The regions of primary crystallization of the phases Fe (8-Fe and y-Fe), and tj are indicated in fig. 3. The absence of any residual Fe is a prerequisite for the attainment of good permanent magnetic properties. This requires that the overall composition of the starting material remains outside the region where primary crystallization of Fe takes place. Schneider et al. (1986a) showed that precautions taken on the basis of the liquidus projection do not always guarantee the absence of... 

The Sm-Co-C system. The liquidus projection and the isothermal section at 900°C of the Sm-Co-C ternary phase diagram have been determined (Stadelmaier and Liu 1985), Nine four-phase reactions occur during crystallization ... 

From liquidus projection, it is known that two ternary phases with composition of YNi2C2, probably, Y5Ni29C3 are present in this system. YNi2C2 melts congruently and has a large field of primary crystallization from the melt, and the phase with a probable composition YjNi29C3 is located between the fields of primary Y2Nij7 and... 

In the polythermal projection of the liquidus surface, monovariant liquidus grooves separate phase regions of primary crystallization and, where available, isothermal lines eontour die liquidus surfaee (see Fig. 3). 

For the liquidus description, the experimental phase equilibria data of [1986Kun] and thermodynamic data of [1978Muk] were used. The liquidus projection shows no invariant reaction. Similar results could be obtained also by using Calphad type parameters given by [1991Har]. 

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