A DOPPLER BROADENING POSITRON-ANNIHILATION SPECTROSCOPY STUDY OF MAGNETICALLY INDUCED RECOVERY IN NICKEL

Doppler broadening positron annihilation spectroscopy and x-ray diffraction have been used to investigate the effects of pulsed magnetic fields on the defect structure of heavily cold worked nickel samples. The experimental variables under investigation include temperature, crystallographic texture, magnetic field strength and frequency. The key results can be summarized as follows: (i) the extent of the magnetically induced recovery, although small compared with that of thermal recovery, is significant; (ii) the pulsed magnetic field appears to have a greater effect on dislocation density than on point-defect concentration; and (iii) texture and temperature are important experimental variables (the effects of pulsing frequency and field strength could not be separated due to experimental limitations).