Perspectives of nanocrystalline materials and metallic glass in pure nickel and nickel base alloys

Abstract

Nanocrystalline (NC or nc) nickel has been pure nickel of submicron sizes. Nickel nanoparticles have potential application in magnetic drug delivery, magnetic and fluorescent tag in biology, hypothermic cancer therapy, contrast agents in magnetic resonance imaging, nano barcodes, and nano-metal inks for printing an ultrafine metal circuit pattern, chemical catalysts, electrically conducting polymers, battery materials, and nickel ceramic composites. These nanocrystals may be pure or alloys have prepared by many routes based on state of usage i.e. either an emulsion form or thin deposition or a surfacing for instant protection. Nanocrystals have a limiting range of size, above which it obeys Hall - Petch relation where as below the range it does not obey Hall - Petch relation. The high density of grain boundaries sometimes have referred the facts have totally dealt by grain boundary activities while for other conditions it has been collective grain phenomenon. Exceptionally high coercivity, strength and alloys to form composite nanocrystals/amorphous duplex structure have raised industrial interest for example high density magnetic recording media for compositions of high coercivity. Transitions of nanocrystalline with amorphous structures have produced composite properties. The strategies of development have showed composite structure to totally amorphous compositions. The context have some metallic glass discussions to understand the chronology of changes and technical view points with reference to crystal to glass transition in pure nickel and nickel base alloys