Peritectic point

Many phase diagrams show another feature. It looks like an upside-down V (i.e. a A) touching a horizontal line. It is a peritectic reaction, and the tip of the A is a peritectic point (see Fig. A1.43). 

The iron-carbon diagram (Fig. A1.37) has a peritectic point. Ring it on the diagram. 

The copper-zinc system shown in Fig. A1.38 has no fewer than five peritectic reactions. Locate them and ring the peritectic points. (Remember that when a single-phase field closes above at a point, the point is a peritectic point.)... 

Let us now consider the crystallization process operating on a composition C2, initially poorer in component 1 this composition falls into the compositional triangle C -2-3. Crystallization begins in primary phase field y" (T = 1225 °C). Precipitation of y" crystals drives the residual liquid radially away from C2 along direction 2-C2. At T = 1100 °C, the composition of the liquid reaches cotectic line Ejii-P, where crystals y " begin to form together with y". At peritectic point P, crystals y" are partially resorbed by reaction with the liquid to form intermediate compound C . However, the peritectic reaction is not completed, because of ex-... 

No peritectic point was noticed with lithium chloride and potassium or sodium chlorides. T. W. Richards and W. B. Meldrum (1917) have also studied ternary mixtures of lithium and sodium chlorides with potassium, rubidium, or caesium... 

PERITECTIC TEMPERATURE. Temperature in a peritectic system at which there is equilibrium between the solid and the remaining melt, the composition of which conforms to the peritectic point, at which the temperature line meets the liquids curve. 

Fig. 6.3 Schematic phase diagram for lamellar PS-PB diblocks in PS homopolymer (volume fraction 0h). where the homopolymer Mv is comparable to that of the PS block (Jeon and Roe 1994). L is a lamellar phase, I, and I2 are disordered phases, M may correspond to microphase-separated copolymer micelles in a homopolymer matrix. Point A is the order-disorder transition.The horizontal lines BCD and EFG are lines where three phases coexist at a fixed temperature and are lines of peritectic points. The lines BE and EH denote the limit of solubility of the PS in the copolymer as a function of temperature.

Thus, in the melting process, the solid hydrate melts by decomposing to solid H2O and a liquid solution. This liquid has the composition given by point p, known as the peritectic point. It is an invariant point, since three phases... 

This kind of reaction is called a peritectic reaction and the point p is called the peritectic point. The temperature TP is called the peritectic temperature. 

This reaction is called the peritectic reaction, and the point p is known as the peritectic point and Tp the peritectic temperature. 

At the peritectic point f the peritectic reaction of AC and BC reacting form both C... 

Trioxane/water has a peritectical point at about 7% water (Figure 5). Additional experiments resulted in an eutectic composition of about 90% water under normal pressure. 

The points Tfus, a and Tfus, b are again the melting points of components A and B. The lines originating from the individual melting points represent the curves of their primary crystallization. The curve of primary crystallization of the component A stops at the peritectic temperature at the peritectic point P. Below the peritectic temperature, the curve... 

The vertical projection of the phase diagram of this system is shown in Figure 3.34. The phase diagram has four planes pc(A), pc(B), pc(C), and pc(ABC), which are the projections of the planes of primary crystallization of the compounds A, B, C, and ABC, respectively. The figurative point of the ternary compound ABC lies outside the plane of its primary crystallization. In contrary to the previous case, the phase diagram of this type has only one ternary eutectic point Ct and two singular points, which are the ternary peritectic points Ptj and Ptj. The boundary lines Ptj-et and Ptj-et represent the simultaneous crystallization of components B and ABC, and C and ABC, respectively. 

There are five ternary eutectic and one peritectic points. The crystallization path of all mixtures, figurative points of which lay inside the triangles BY-A3B2X3Y2-BX2 and A3B2X3Y2-P-BX2, starts with the primary crystallization of BY, A3B2X3Y2, or BX2, followed by the crystallization of the neighboring salt till the peritectic point P is reached. 

The phase diagram was calculated from the binary boundaries and from the quaternary mixtures measured, therefore the standard deviation of the fit is not given. The calculated phase diagram of this system is shown in Figure 3.53. The experimentally determined phase diagram measured by Chernov and Ermolenko (1973) is probably not quite correct because of little experimental data in the region of the presented peritectic point. 

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