Electrodeposited Nanocrystalline Metals, Alloys, and Composites

Nanocrystalline growth and grain-size effects in Au–Cu electrodeposits

“…With reference to the To form a nanocrystalline electrodeposited foil, the concept is to promote massive nucleation with reduced grain growth. [13,21] The nanocrystalline grain size can be metastable as annealing above 150 °C is shown to yield exothermic reactions in differential scanning calorimetry traces that are associated with grain growth and ordering of the Au-Cu alloy. [19] The refinement of grain size to the nanoscale is shown to enhance the microhardness of electrodeposits in accordance with a Hall-Petch behavior.…”

“…[19] The refinement of grain size to the nanoscale is shown to enhance the microhardness of electrodeposits in accordance with a Hall-Petch behavior. [13,[22][23][24][25] At some level of grain refinement, perhaps below 5-10 nm, the flow stress and hardness are thought to decrease as a mechanism shift occurs from grain boundary strengthening to that of sliding. [12,[22][23] At present, a lower bound of ~6 nm may appear for the present Au-Cu electrodeposits.…”

“…[13] Whereas grain growth is favored at a low cell potential with high surface diffusion, a high cell potential with low surface diffusion promotes nuclei formation. A pulsed current can facilitate nuclei formation as the peak current density can be considerably higher than the limiting direct-current density.…”

Characterization of the passive films on electrodeposited Fe-Ni-Cr alloys in borate solution at pH 8.4

“…Further investigation may reveal whether the ability of the electrodeposited Fe-Ni-Cr alloy offers protection against non-uniform pitting corrosion as has been observed for other amorphous/microcrystalline materials recorded in the literature [8,11]. In the literature, research illustrates the structure-property relationship of electrodeposited iron based alloys of various compositions produced with different deposition variables [35,36].…”

“…This was confirmed in our earlier work [7] using alloys of composition Fe 50 Ni 25 Cr 25 passivated in sulphuric acid. However, higher passive current densities have been recorded for nanocrystalline materials, [8,9] and this has been attributed by the researchers to either the passive film being more defective or thinner compared to films formed on polycrystalline materials. The authors also noted that enhanced stability of the passive layer against local corrosion has been reported by other researchers for nanocrystalline Fe-Ni-Cr alloys [10,11].…”