What is the effect of annealing on the defects present in the sample? Does it remove defects in the sample? Is there any chance that due to annealing the point defects present in the sample combine to form a large size void?
Annealing activates solid-state diffusion which allows interstitials to find and occupy point vacancies. It also tends to release dislocation pileups at grain boundaries by enabling the growth of new, stress-free grains, for which the activation energy is at least partly furnished by the strain energy contained in the pileups.
The atom movements within the lattice are not sufficient to eliminate macroscopic voids of the sort caused by manufacturing errors (slag inclusions, folding voids, etc.). However, in the case of sintering metal powders, it is possible to produce metal parts which start out microscopically porous in the "green state" (as cold-pressed powder) and wind up ~99% fully dense.