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Oxide dispersion strengthened nickel (ODS-Ni) electrodeposits were fabricated to net shape using the lithography, electroforming, and molding (LIGA) process in a nickel sulfamate bath containing a suspension of 10 nm diameter Al2O3 particulates. Mechanical properties were compared to baseline specimens fabricated using an identical sulfamate bath chemistry without the particulates. Results revealed that the as-deposited ODS-Ni exhibited significantly higher yield strength and ultimate tensile strength (∼ 50 pct) than the baseline material. This increase in as-deposited strength was attributed to Orowan strengthening. The ODS-Ni also showed improved retention of room-temperature strength after annealing over a range of temperatures up to 600°C. Nanoindentation measurements revealed that the properties of the dispersion-strengthened deposit were uniform through its thickness, even in narrow, high aspect ratio structures. Microscopy revealed that this resistance to anneal softening was due to an inhibition of grain growth in the presence of the oxide dispersion. At elevated temperatures, the strength of the ODS-Ni was approximately 3 times greater than that of the baseline material although with a significant reduction in hot ductility. [ABSTRACT FROM AUTHOR]

This paper presents the results of a nano-indentation study of the effects of strain gradient plasticity on the elastic-plastic deformation of LIGA Ni MEMS structures plated from sulfamate baths. Both Berkovich and North Star indenter tips were used in the study to investigate possible effects of residual indentation depth between the micro and nano scales on the hardness of LIGA Ni MEMS structures. A microstructural length scale parameter, l = 0.89 μm, was determined for LIGA nickel films. This is shown to be consistent with a stretch gradient length scale parameter, ls, of ∼0.36 μm. [ABSTRACT FROM AUTHOR]

Presents a study which investigated the effects of strain gradient plasticity on the elastic-plastic deformation of lithographie, galvanoformung, abformung nickel microelectromechanical systems plated from sulfamate baths. Review of related literature; Methodology; Results and discussion.

This paper presents results of an experimental study of fatigue in LIGA Ni micro-electro-mechanical systems (MEMS)/thin films produced by electroplating from a sulfamate bath at a current density of 50 mA/cm2. Following a brief description of microstructure and micro-tensile properties, the results of stress-life (S-N) experiments are presented for specimens with thicknesses of 70 and 270 μm. Specimens with the thicker cross-sections (270 μm thick) are shown to have comparable fatigue resistance to annealed bulk Ni in the as-plated condition. The thinner specimens (70 μm thick) have comparable fatigue resistance to hardened Ni, and better fatigue resistance than the thicker samples. The underlying fatigue fracture modes are elucidated via scanning electron microscopy. The implications of the results are then discussed for the failure analysis of LIGA Ni MEMS structures. [Copyright &y& Elsevier]