Need help in hurry about phase transformations

[LynnCGL]

I'm studying in a class about phase transformations, and have a couple of questions needing answers/clarification:

N0.1

A metallic sample can show faceing when heated, but a plastic sample does not because_______?

NO.2

a)What are the general energies associated with a small precipitate of phase β inside a matrix phase α.（Assume spherical precipitates initially）

b)Often, a small precipitate starts as a coherent one,then is loses coherency as it grows beyond a certain critical radius(r).Explain this observation briefly and illustrate with a schematic plot.

c)If the stable shape of the precipitate tends to become plate or disc shaped (e.g.figure 2),what can you comment about the interfacial energies involved?

and the last questin also showed on the pic.

Need help,thank you very much

 

[Navin A S]

.A1. A plastic sample does not show facing when heated because plastics are not crystalline materials, and facing is a phenomenon associated with crystalline materials as they undergo phase transformation.A2a. The general energies associated with a small precipitate of phase β inside a matrix phase α are the sum of the strain energy associated with the deformation of the matrix phase, the interfacial energy between the two phases, and the elastic energy stored in the precipitate.A2b. As a precipitate grows beyond a certain critical radius (r), it loses coherency due to increased elastic strain energy. This can be illustrated with a schematic plot showing the change in energy as a function of precipitate size.A2c. If the stable shape of the precipitate tends to become plate or disc shaped, this indicates that the interfacial energy between the two phases is relatively low, which is necessary for the formation of larger precipitates.