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Magnetic Smart Tags (MaST) for Arms Control and Treaty Verification

Langlois, Eric L.; Pillars, Jamin R.; Monson, Todd M.; Arrington, Christian L.; Finnegan, Patrick S.; St John, Christopher S.; Smartt, Heidi A.

The ability to track nuclear material is a challenge for resiliency of complex systems, e.g., harsh environments. RF tags, frequently used in national security applications, cannot be used for technological, operational, or safety reasons. Magnetic Smart Tags (MaST) is a novel tag technology based on magnetoelastic sensing that circumvents these issues. This technology is enabled by a new, cost-effective, batch manufacturing electrochemical deposition (ECD) process. This new advancement in fabrication enables multi-frequency tags capable of providing millions of possible codes for tag identification unlike existing theft deterrent tags that can convey only a single bit of information. Magnetostrictive 70% Co: 30% Fe was developed as the base alloy comprising the magnetoelastic resonator transduction element. Saturation magnetostriction, S , has been externally measured by the Naval Research Laboratory to be as high as 78 ppm. Description of a novel MEMS variable capacitive test structure is described for future measurements of this parameter.

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TYPE SAND Report YEAR 2016
OSTIDOI

Fatigue stress concentration and notch sensitivity in nanocrystalline metals

Journal of Materials Research

Furnish, Timothy A.; Boyce, Brad B.; Sharon, John A.; O'Brien, Christopher J.; Clark, Blythe C.; Arrington, Christian L.; Pillars, Jamin R.

Recent studies have shown the potential for nanocrystalline metals to possess excellent fatigue resistance compared to their coarse-grained counterparts. Although the mechanical properties of nanocrystalline metals are believed to be particularly susceptible to material defects, a systematic study of the effects of geometric discontinuities on their fatigue performance has not yet been performed. In the present work, nanocrystalline Ni-40 wt%Fe containing both intrinsic and extrinsic defects were tested in tension-tension fatigue. The defects were found to dramatically reduce the fatigue resistance, which was attributed to the relatively high notch sensitivity in the nanocrystalline material. Microstructural analysis within the crack-initiation zones underneath the defects revealed cyclically-induced abnormal grain growth (AGG) as a predominant deformation and crack initiation mechanism during high-cycle fatigue. The onset of AGG and the ensuing fracture is likely accelerated by the stress concentrations, resulting in the reduced fatigue resistance compared to the relatively defect-free counterparts.

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TYPE Journal Article YEAR 2016
ScopusOSTIDOI

Electrodeposition of high magnetostrictive cobalt-iron alloy films for smart tags and sensor applications

Pillars, Jamin R.

Magnetostrictive CoFe films were investigated for use as magnetoelastic tags or sensors. The ability to electrodeposit these films enables batch fabrication processes to pattern a variety of geometries while controlling the film stoichiometry and crystallography. In current research looking at CoFe, improved magnetostriction was achieved using a co-sputtering, annealing, and quenching method1. Other current research has reported electrodeposited CoFe films using a sulfate based chemistry resulting in film compositions that are Fe rich in the range of Co0.3-0.4Fe0.7-0.6 and have problems of codeposition of undesirables that can have a negative impact on magnetic properties. The research presented here focused on maximizing magnetostriction at the optimal stoichiometry range of Co0.7-0.75Fe0.3-0.25, targeting the (fcc+bcc)/bcc phase boundary, and using a novel chemistry and plating parameters to deposit films without being limited to “line of sight” deposition.

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TYPE Thesis or Dissertation YEAR 2015
OSTI
Results 26–50 of 60
Results 26–50 of 60