Improved Hardness and Thermal Stability of Nanocrystalline Nickel Electrodeposited with the Addition of Cysteine

Abstract

Experiments were conducted for the study of the effect of cysteine addition on the microstructure of nanocrystalline Ni films electrodeposited from a nickel sulfate-based bath. Furthermore, the thermal stability of the nanostructure of Ni layers processed with cysteine addition was also investigated. It was found that with increasing cysteine content in the bath, the grain size decreased, while the dislocation density and the twin fault probability increased. Simultaneously, the hardness increased due to cysteine addition through various effects. Saturation in the microstructure and hardness was achieved at cysteine contents of 0.3–0.4 g/L. Moreover, the texture changed from (220) to (200) with increasing the concentration of cysteine. The hardness of the Ni films processed with the addition of 0.4 g/L cysteine (∼6800 MPa) was higher than the values obtained for other additives in the literature (<6000 MPa). This hardness was further enhanced to ∼8400 MPa when the Ni film was heated up to 500 K. It was revealed that the hardness remained as high as 6000 MPa even after heating up to 750 K, while for other additives, the hardness decreased below 3000 MPa at the same temperature.

Combinatorial Study of Phase Composition, Microstructure and Mechanical Behavior of Co-Cr-Fe-Ni Nanocrystalline Film Processed by Multiple-Beam-Sputtering Physical Vapor Deposition

“…Such high values can also be obtained in pure electrodeposited metal films if the electrolyte bath contains high concentration of organic additives. For example, saccharin or cysteine additives resulted in dislocation densities of about 200–600 × 10 14 m −2 and twin fault probability of 3–4% in Ni layers [ 43 , 44 ]. This indicates that the high lattice defect density observed for the present sample is not a unique feature of CCA thin films.…”

Reliability and interpretation of the microstructural parameters determined by X-ray line profile analysis for nanostructured materials

“…It is worth noting that extremely high dislocation density (∼ 600 × 10 14 m −2 ) and large twin fault proba-bility (∼ 3.6%) can be detected in electroplated Ni even without alloying elements [71]. Namely, the addition of organic additives, such as saccharin or cysteine, to the electrolyte bath can reduce the grain size to about 20 nm which was accompanied by the development of a high dislocation density and twin fault probability during electrodeposition [71,72]. The very small grain size and the large defect density yielded an extremely high hardness of about 7 GPa in Ni.…”

“…It is noticed that short post-processing heat treatment at moderate temperatures (at the homologous temperature of about 0.35) can result in an additional increase in hardness without reducing the ductility for nanomaterials processed by either SPD or bottom-up techniques [6]. For instance, in Ni deposited from a bath containing 0.4 g/L cysteine warming up to 500 K yielded an increase of the hardness from ∼ 7 to ∼ 8.4 GPa [71]. For highly alloyed nanomaterials, the optimum annealing temperature and the maximum hardening due to heat treatment increase.…”

Advances in Micro- and Nanomechanics

“…Here authors proposed a new relatively simple approach based on the consideration of deformations of bilayer cantilevers. The analysis of the thermal stability and hardness of nanocrystalline Ni thin films was given in [6]. Here it was shown that the addition of cysteine results in improved hardness of films.…”