Majorana Electroformed Copper Mechanical Analysis

The MAJORANA DEMONSTRATOR is a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay. The DEMONSTRATOR will utilize ultra high purity electroformed copper for a variety of detector components and shielding. A preliminary mechanical evaluation was performed on the Majorana prototype electroformed copper material. Several samples were removed from a variety of positions on the mandrel. Tensile testing, optical metallography, scanning electron microscopy, and hardness testing were conducted to evaluate mechanical response. Analyses carried out on the Majorana prototype copper to this point show consistent mechanical response from a variety of test locations. Evaluation shows the copper meets or exceeds the design specifications

Characterization of U-Mo Foils for AFIP-7

Twelve AFIP in-process foil samples, fabricated by either Y-12 or LANL, were shipped from LANL to PNNL for potential characterization using optical and scanning electron microscopy techniques. Of these twelve, nine different conditions were examined to one degree or another using both techniques. For this report a complete description of the results are provided for one archive foil from each source of material, and one unirradiated piece of a foil of each source that was irradiated in the Advanced Test Reactor. Additional data from two other LANL conditions are summarized in very brief form in an appendix. The characterization revealed that all four characterized conditions contained a cold worked microstructure to different degrees. The Y-12 foils exhibited a higher degree of cold working compared to the LANL foils, as evidenced by the highly elongated and obscure U-Mo grain structure present in each foil. The longitudinal orientations for both of the Y-12 foils possesses a highly laminar appearance with such a distorted grain structure that it was very difficult to even offer a range of grain sizes. The U-Mo grain structure of the LANL foils, by comparison, consisted of a more easily discernible grain structure with a mix of equiaxed and elongated grains. Both materials have an inhomogenous grain structure in that all of the characterized foils possess abnormally coarse grains

Characterization of U-Mo Foils for AFIP-7

Twelve AFIP in-process foil samples, fabricated by either Y-12 or LANL, were shipped from LANL to PNNL for potential characterization using optical and scanning electron microscopy techniques. Of these twelve, nine different conditions were examined to one degree or another using both techniques. For this report a complete description of the results are provided for one archive foil from each source of material, and one unirradiated piece of a foil of each source that was irradiated in the Advanced Test Reactor. Additional data from two other LANL conditions are summarized in very brief form in an appendix. The characterization revealed that all four characterized conditions contained a cold worked microstructure to different degrees. The Y-12 foils exhibited a higher degree of cold working compared to the LANL foils, as evidenced by the highly elongated and obscure U-Mo grain structure present in each foil. The longitudinal orientations for both of the Y-12 foils possesses a highly laminar appearance with such a distorted grain structure that it was very difficult to even offer a range of grain sizes. The U-Mo grain structure of the LANL foils, by comparison, consisted of a more easily discernible grain structure with a mix of equiaxed and elongated grains. Both materials have an inhomogenous grain structure in that all of the characterized foils possess abnormally coarse grains

Yielding and fracture in nanolayered metallic composites

Thin films are currently being used in virtually all forms of electronic devices, as protective coatings, MEMS and even some drug delivery systems. In many cases the strength of films becomes a critical factor in their reliability. For this reason, a better understanding of their mechanical properties is needed. Multilayer metallic films in particular exhibit higher strengths than the constituents alone. This work utilized bulge testing in conjunction with nanoindentation to study the elastic properties, the onset of yielding, and eventual failure of several multilayered film systems and geometries. CuNb, CuNi and CuNbNi multilayers with individual layer thicknesses of 20nm were studied. Though the CuNi films had extremely poor adhesion strength, these films had the highest pressures needed to cause fracture , reaching values approximately 1/3 higher than the CuNb and CuNbNi films. However, the CuNb films were shown to exhibit higher hardnesses than the CuNi and CuNbNi films. These differences were attributed to a difference in the strain hardening abilities of these films. The information found from this work will serve to be the base line for fatigue testing of these films in the future

The effects of chemistry and microstructure on the strengthening behavior of nanolayered metallic films

Bellou, A. et at. (2010, March 26). Poster presented at the Washington State University Academic Showcase, Pullman, WA. ; Funding: This work was funded by the Division of Materials Science and Engineering, Office of Basic Energy Science at the DOE under grant number DE-FG02-07ER46435

Hot Rolling of ZK60 Magnesium Alloy with Isotropic Tensile Properties from Tubing Made by Shear Assisted Processing and Extrusion (ShAPE)

In the present work, we utilized Shear Assisted Processing and Extrusion (ShAPE), a solid-phase processing technique, to extrude hollow tubes of ZK60 Mg alloy. Hot rolling was performed on these as-extruded tubes (after slitting them longitudinally) to thickness reductions of 37%, 68%, and 93% to investigate their viability as rolling feedstock material. EBSD analysis showed the formation of twinned grains in the ShAPE processed material and a gradual re-orientation of the basal texture parallel to the extrusion direction with each rolling step. Moreover, an equiaxed grain size of 5.15 ± 3.39 μm was obtained in the ShAPE extruded material, and the microstructure was retained even after 93% rolling reduction. The rolled sheets also showed excellent tensile strengths and no mechanical anisotropy, a critical characteristic for formability. The unique microstructures developed and their excellent mechanical properties, combined with the ease of scalability of the process, make ShAPE a promising alternative to existing methods for producing rolling feedstock material

Palladium(II)-Catalyzed Enantioselective Synthesis of 2-Vinyl Oxygen Heterocycles

2-Vinylchromanes (<b>1</b>), 2-vinyl-1,4-benzodioxanes (<b>2</b>), and 2,3-dihydro-2-vinyl-2<i>H</i>-1,4-benzoxazines (<b>3</b>) can be prepared in high yields (90–98%) and excellent enantiomeric purities (87–98% ee) by [COP-OAc]₂-catalyzed cyclization of phenolic (<i>E</i>)-allylic trichloroacetimidate precursors. Deuterium-labeling and computational experiments are consistent with these cyclization reactions taking place by an <i>anti</i>-oxypalladation/<i>syn</i>-deoxypalladation mechanism. 2-Vinylchromanes can also be prepared in good yields and high enantiomeric purities from analogous (<i>E</i>)-allylic acetate precursors, which constitutes the first report that acetate is a competent leaving group in COP-catalyzed enantioselective S_N2′ substitution reactions

Bond coat assisted enhancement in microstructural, mechanical and corrosion behavior of AZ91 magnesium alloy cold spray coated with aluminum alloys

Cold spray coating technique was used to deposit coatings of AA6061 aluminum alloy on AZ91 magnesium alloy substrates. A bond coat of commercially pure aluminum was used to facilitate deposition of the AA6061 powders. Two cold spray coating iterations were conducted to optimize the coating’s microstructural features such as porosity, surface roughness, and interface microstructure. Mechanical properties such as hardness, wear resistance, and adhesion behavior were characterized and used as metrics to compare the coatings with the substrate. The corrosion behavior of the coated and uncoated samples was characterized using multiscale and multimodal corrosion measurements comprising macroscopic potentiodynamic polarization and scanning electrochemical cell microscopy. The coated substrates exhibited a significant improvement in mechanical and corrosion performance as compared to the uncoated substrate