The eutectoid reaction. The eutectoid reaction describes the phase transformation of one solid into two different solids. In the Fe-C system, there is a eutectoid point at approximately 0.8wt% C, 723°C. The phase just above the eutectoid temperature for plain carbon steels is known as austenite or gamma.

Atomic Percent Tin Phase diagram of Gold-Tin has seven distinct phases, three peritectics, two eutectics, and one eutectoid reactions. Figure by MIT OCW. • We saw last time that a homogeneous solution can spontaneously decompose into phase-separated mixtures when interactions between the molecules are unfavorable.

A phase diagram for a fictitious binary chemical mixture (with the two components denoted by A and B) used to depict the eutectic composition, temperature, and point. (L denotes the liquid state.)

• Phase diagrams are useful tools to determine:--the number and types of phases,--the wt% of each phase,--and the composition of each phase for a given T and composition of the system. • Alloying to produce a solid solution usually--increases the tensile strength (TS)--decreases the ductility. • Binary eutectics and binary eutectoids ...

transformation is also often called eutectoid transformation. • Understanding of the different phases of iron-carbon (Fe-C) steel. • What is the eutectoid transformation? How to understand such a transformation in Fe-C steel, particularly regarding the phase diagram? About cellular transformation (or precipitation)

2023年1月16日 · A phase diagram for two immiscible solids and the liquid phase (which is miscible in all proportions) is shown in Figure \(\PageIndex{1}\). The point labeled “e 2 ” is the eutectic point , meaning the composition for which the mixture of …

Figure 30-19: Construct the peritectic over eutectic phase diagram. In all cases, you should be able to predict how the phase fractions and equilibrium compo- sitions change as you reduce the temperature at equilibrium.

The eutectoid reaction. The compositions of the two new phases are given by the ends of the tie-line through the eutectoid point. The general eutectoid reaction is therefore: Solid γ –> solid α + solid β. or using the names given to these phases: Austenite –> ferrite + cementite (Fe 3 C) <

The eutectoid structure in iron has a special name: it is called pearlite (because it has a pearly look). The schematic and micrograph below show pearlite. It is important to note that pearlite is not a phase, but a mixture of two phases: ferrite and cementite.

The eutectoid (eutectic-like in Greek) reaction is similar to the eutectic reaction but occurs from one solid phase to two new solid phases. Eutectoid Reactions