Observation of the substructure of weakly deformed polycrystalline nickel

The paper describes the results of observing the substructure and measuring the subgrain size of polycrystalline nickel of purity 99·80% for a tensile deformation of 0·5–10%. It was found that a rapid decrease in the average grain size occurs already at small degrees of deformation. The deformation at which subgrains begin to form is identical with the critical deformation of recrystallization and in the case of nickel of the above purity it is 2% of the elongation. From 5% there are dislocations even inside the subgrains and in some places dense clusters are formed.