Using two alternative approaches to describing the defect structure of dislocation-free copper single crystals (the classical theory of the nucleation and growth of particles of the second phase in solids and Vlasov’s model for solids), we demonstrated that high-temperature precipitation of impurities occurs upon cooling of a growing crystal. High-temperature precipitation of impurities can lead to further development of a defective structure due to the formation of dislocation loops, microvoids (or micropores), dislocations, etc.