This cast sample of a Copper-4wt%Tin bronze shows a grain structure with traces of cored dendrites.

The coarse grain structure is due to grain growth after solidification. Coring develops due to non-equilibrium solidification of the casting, which causes a non-uniform distribution of the alloying elements.

The coring could be removed by a high temperature annealing heat treatment to allow redistribution of the copper and tin. The sample also contains a number of pores (the dark regions).