Phase Stability In Cobalt Nanowires Prepared By A Template Electrodeposition Process

Cobalt is an important magnetic element, its excellent magneticproperties showed by nano-scale have a good prospect of application.Meanwhile, Cobalt has a typical fcc to hcp martensitic phase transformation.The pure cobalt system is an ideal system for martensitic research. Studieshave shown that the martensitic transformation temperature and phasestability are associated with the size of the material. With the grain orparticle size is reduced to the nanometer level, Msdecreased significantlyimproved the stability of fcc at a low temperature. The studies have mainlyfocused on the size effect in the martensite phase transition, while thediscussion in the reverse transformation is seldom. Also, shape factor hasnot been taken into account while discussing the effect of size. Thisresearch fabricated single crystal nanowires nanowire with four differentdiameters (40nm, and55nm,70nm,90nm) through the template electrodeposition method followed with discussion on growth mechanisms andorientation. In situ XRD data shows that70-90nm is probably the criticalsize of size effect in reverse martensitic transformation. Hcp phase can bemore stable than coarse-grained Cobalt increased Asmore than200degreeswhen the diameter is under70nm.That is to say, the reverse martensitictransformation has been greatly inhibited. In this paper, through analysisand discussion, we proposed that martensitic transformation in nanoscaleneed to explore the introduction of the shape effect.