reannealing

Reannealing is the process of annealing a material again after an initial heat treatment or after an intermediate processing step. It is used to relieve or reset properties altered by prior treatments—such as deformation, irradiation, or chemical exposure—without melting the material. Reannealing typically involves heating to a temperature below the melting point, holding for a period, and then cooling, with exact conditions determined by the material and the desired outcome.

In metallurgy and materials engineering, reannealing follows cold working or irradiation to restore ductility and reduce residual stresses, or to modify the microstructure through recrystallization or grain growth. Reannealing cycles may be employed after successive forming operations to maintain workability and tailor mechanical properties.

In semiconductor processing, reannealing refers to additional annealing steps after ion implantation to repair lattice damage and activate dopants. Rapid thermal or flash annealing methods are often used to limit unwanted diffusion during reannealing.

In glass and polymers, reannealing helps relieve internal stresses and reduce birefringence in glass and can promote stress relaxation in certain polymers. Repeated annealing can influence properties such as toughness, hardness, and dimensional stability.

In biology, reannealing describes the renaturation of complementary DNA strands after denaturation, a process central to many molecular biology techniques.