DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click HERE
to register or log in.
Effect of Nickel Content on the Crystallization Behavior in Nanocrystalline (CO1-XNIX)88ZR7B4CU1 Soft Magnetic Alloys
ALABAMA UNIV TUSCALOOSA DEPT OF METALLURGICAL AND MATERIALS ENGINEERING
Pagination or Media Count:
A series of Co1-xNix88Zr7B4Cu1 soft magnetic alloys, where X was varied from 0 to 1, were fabricated by a melt spinning process into thin ribbons of the material. This process was followed by an isothermal anneal to produce a nanocomposite alloy, i.e. nanocrystalline grains in a residual amorphous matrix. The alloy series was designed to investigate crystallization kinetics and limits to the compositional regime where a nanocomposite could be formed. The primary and secondary crystallization temperatures of each alloy were determined using Differential Scanning Calorimetry DSC from which the crystallization activation energies were calculated using the Kissinger Method. When X exceeded 0.75, the as-spun ribbons exhibited partial crystallization, resulting in reduced exothermic crystallization peaks. For lower Ni contents, the ribbons were amorphous in the as-spun state. The activation energy for crystallization decreased with increasing Ni content. Transmission Electron Microscopy TEM and Atom Probe Tomography APT revealed fine nanocrystallite and boron segregation to the grain boundaries with increasing Ni content. The previously suspected use of Cu clustering, which can act as heterogeneous nucleation sites, showed no clear correlation with observed spatial location of the crystallites. Chemical partitioning between species in the as-spun and primary crystallization heat treatments were correlated to the resulting changes in magnetic properties. As Ni content increased, the saturation magnetization and normalized magnetization for these samples decreased accordingly.
APPROVED FOR PUBLIC RELEASE