Nucleation of recrystallized grains in heavily cold-worked α-brass

Abstract

The effect of heating on the substructure of heavily rolled 70:30 brass is described. Colonies of very fine ‘recovery’ twins (0.002–0.01 μm thick) develop in the shear bands at an early stage of heating and subsequently grow lengthwise in the matrix. Dislocation loss from the matrix regions associated with the recovery twins is gradual and the nuclei for recrystallization are not developed until well after the twins have formed. Nucleation appears to occur by lateral growth of either the twins or matrix regions but in the early stages of this growth there is no clear boundary distinguishing the potential nucleus from the cold-worked matrix. Examination of specimens deformed in torsion shows that similar changes occur in slowly heated specimens. The results are discussed with reference to the currently accepted view that the return of short-range order is the major contributory factor to the release of stored energy from coldworked 70:30 brass prior to recrystallization.