Solidification peritectic

Because a peritectic transformation requires solid-state diffusion as P reacts with the liquid phase to convert to a, it tends to be more sluggish than a eutectic reaction. As the a phase builds up as a layer between the and liquid phases, solid-state 

FIGURE 6.39 (a) Peritectic phase diagram, b) Schematic illustration of phase formation 

---

J. Tiaden, B. Nestler, H. J. Diepers, I. Steinbach. Physica D 115 11, 1998 G. J. Schmitz, B. Nestler. Simulation of phase transitions in multiphase systems, peritectic solidification of YBaCuO-superconductors. Mater Sci Eng B 53 11, 1998. 

A peritectic solidification process is illustrated in Figure 6.39 and can be exemplified by the following reaction ... 

Describe various types of solidification processes and apply information from phase diagrams to predict the type of microstructures that can arise from common isomorphous, eutectic, and peritectic solidification events. 

Two approaches have been taken to produce metal-matrix composites (qv) incorporation of fibers into a matrix by mechanical means and in situ preparation of a two-phase fibrous or lamellar material by controlled solidification or heat treatment. The principles of strengthening for alloys prepared by the former technique are well estabUshed (24), primarily because yielding and even fracture of these materials occurs while the reinforcing phase is elastically deformed. Under these conditions both strength and modulus increase linearly with volume fraction of reinforcement. However, the deformation of in situ, ie, eutectic, eutectoid, peritectic, or peritectoid, composites usually involves some plastic deformation of the reinforcing phase, and this presents many complexities in analysis and prediction of properties. 

At/ the final solidification takes place through a peritectic reaction AC and BC crystallise out together at the expense of liquid and portion of C. This can easily be seen from die Alkemade triangle C-AC-BC. During the peritectic reaction, the mean solid composition moves from k to p. 

Chuang Y. K. Reinisch R. Schwerdtfeger K., Kinetics of the diffusion controlled peritectic reaction during solidification of iron-carbon alloys. Metall. Trans. A, 6(1975) 235-238... 

In general, the peritectic formation of the Nd2Fei4B phase is preferred to that of the y-Fe phase under the higher cooling rate in the rapid solidification method. This phenomenon can be understood from the fact that the formation of the y-Fe phase requires a long diffusion distance for Fe atoms, which naturally requires that the materials be kept at sufficiently high temperature during the development of the microstructure. 

Many inorganic hydration salts show an unharmonic melting phenomenon (peritectic reaction). Upon solidification, they are formed by the reaction between the lower hydration salts and the liquid. The lower hydration salts of inorganic salts in aqueous solutions exhibit generally greater density than the liquid phase and precipitate at the bottom of the container. As shown in Fig. 1 (a) [3], they separate into the solid S and... 

In the previous chapter the solidification of single-phase metals and alloys was considered with regard to both the constitutional and structural effects which occurred. In this chapter more complex alloys are treated in which two or more phases are present. Eutectics, peritectics and monotectics are considered first. Particles in melts and gases in melts are dealt with subsequently. 

Multiphase solidification eutectics, 70 gases in melts, 90 monotcctics, 86 particles in melts, 88 peritectics, 83... 

---