If the material is fast-cooled, the structure consists entirely of beta phase. During a slower cool, the alpha precipitates out of solution at the crystal boundaries, forming a structure of beta dendrites surrounded by alpha. This structure is called a Widmanstatten structure, because a geometrical pattern of alpha is formed on the certain crystallographic orientations of the beta lattice. The wrought, two phase material consists of grains of beta and alpha. Hot rolling tends to elongate the grains in the rolling direction.
Brasses frequently contain lead in order to improve machinability.
The microstructure of the leaded brasses is similar to that of the unleaded brasses with the addition of almost pure lead particles found in the grain boundaries and inter-dendritic spacings. The lead is observed in the microstructure as discrete, globular particles because it is practically insoluble in solid copper. The number and size of the lead particles increases with increasing lead content.