Stored energy in nanocrystalline Ni-Mo films processed by electrodeposition

The energy stored in the crystallographic defects in nanocrystalline Ni-Mo alloy films was determined experimentally by differential scanning calorimetry (DSC) and compared with the calculated values. Two Ni-Mo layers with low (∼0.4 at.%) and high (∼5.3 at.%) Mo contents were processed by electrodeposition. It was revealed that the majority of the heat released during DSC (∼77%) was related to the grain boundaries. It was also found that the increase of Mo content from 0.4 to 5.3 at.% yielded an enhancement of the stored energy with a factor of about two. The measured and the calculated stored energies were compared with the values obtained for ultrafine-grained Ni-Mo alloys with similar compositions but processed by severe plastic deformation (SPD). It was revealed that in the SPD-processed samples there was a considerable contribution of vacancies to stored energy while their effect in the electrodeposited layers was lower.