Chapter 9-15

The copper-zinc phase diagram:Terminal and Intermediate Solid Solutions

Terminal solid solutions

intermediate solid solutions

Commercial brasses are copper-rich copper-zinc alloys. For example, cartridge brass is 70 wt% copper-30 wt% zinc

Chapter 9-16

The magnesium-lead phase diagram:

like two simple eutectic diagrams joined back to back

Intermetallic compound (with distinct chemical formula), NOT a solid solution.It is 19 wt% Mg-81 wt% Pb

Melting temperature of Mg2Pb 550 oC)

Extensive solubility of Pb in Mg

Limited Mg solubility

can be considered as a component of the phase diagrams

Chapter 9-15

EUTECTIC and PERITECTIC REACTIONS

• Eutectic transformation also called eutectic reaction• A eutectic reaction is an invariant reaction, and a eutectic point is also called an invariant point• the horizontal tie line at the eutectoid temperature is termed a eutectoid isotherm• Point P represents a peritectic reaction