Lead (Pb) is alloyed with Tin (Sn) to make solders. A wide range of alloy compositions are used, giving different melting points and ranges of workability (i.e. temperatures where the alloys is a mushy solidifying mixture of liquid and solid crystals).

The microstructures that develop can be predicted using phase diagrams, an example of which are given below. The phase diagram (and an understanding of the kinetics or rate of development of the microstructure) are important tools for the design of alloys for different applications.

Lead-Tin (Pb-Sn) Equilibrium Phase Diagram