Structural changes in cryogenically deformed copper during long-term (up to two years) room-temperature ageing were investigated. It is found that the structure formed under high (e=8.2) cryogenic deformation is unstable and is characterized by abnormalous grain growth. It is shown that the grain growth is preceded by a long (up to a year) incubation period. It is revealed that the structure rapidly losses stability with an increase in accumulated cryogenic strain
