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Investigation of alloying effects in aluminum dispersion strengthened with Al$sub 2$O$sub 3$

Description: Two types of alloying elements were investigated to determine if the room-temperature strength could be improved and if, through lowering the oxide content, the high-temperature ductility could be improved. Mg was investigated for its solid solution strengthening in one type alloy. The other type alloy involved further dispersion strengthening through adding Fe, Mo, Zr, Cr, V, and Ti which form highly stable intermetallic compounds with Al. Fabrication techniques were developed which produced uniform and reproducible rods for testing. Prealloyed powders were produced by atomizing the molten alloys and collecting the powders in water. This procedure produced uniform powders with a very fine distribution of the intermetallic compounds. Fabrication into rods then included ball-milling, vacuum hot pressing, vacuum heat treating, and hot extrusion. Mg additions improved strengths up to 200$sup 0$C with little effect above that temperature. Room-temperature tensile strengths up to 77,000 psi were obtained which are comparable to the strengths obtained in conventional aluminum alloys. The additional dispersion strengthening of the intermetallic compounds is additive to that of the oxide from room temperature to 450$sup 0$C. No significant improvements in ductility are obtained by reducing the oxide content since even at very low ball-milling times (i.e., low oxide contents) the uniform elongation at 450$sup 0$C is typically 0.5 percent. Good combinations of strength and ductility at 450$sup 0$C were obtained in some of the alloys containing intermetallic compounds with no ball-milling. Typical properties at this temperature were tensile strengths of 7,000 psi, uniform elongation of 3 percent, and total elongation of 35 percent. (21 tables, 33 fig, 43 references) (auth)
Date: October 1, 1975
Creator: Copeland, G. L.
Partner: UNT Libraries Government Documents Department
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Investigation of the effects of intense pulsed particle beams on the durability of metal-to-plastic interfaces.

Description: We have investigated the potential for intense particle beam surface modification to improve the mechanical properties of materials commonly used in the human body for contact surfaces in, for example, hip and knee implants. The materials studied include Ultra-High Molecular Weight Polyethylene (UHMWPE), Ti-6Al-4Al (titanium alloy), and Co-Cr-Mo alloy. Samples in flat form were exposed to both ion and electron beams (UHMWPE), and to ion beam treatment (metals). Post-analysis indicated a degradation in bulk properties of the UHMWPE, except in the case of the lightest ion fluence tested. A surface-alloyed Hf/Ti layer on the Ti-6Al-4V is found to improve surface wear durability, and have favorable biocompatibility. A promising nanolaminate ceramic coating is applied to the Co-Cr-Mo to improve surface hardness.
Date: February 1, 2005
Creator: Prasad, Somuri V.; Renk, Timothy J.; Provencio, Paula Polyak; Petersen, Donald W. (University of Alabama, Birmingham, AL); Petersen, Thomas D. (University of California, San Diego, CA); Buchheit, Thomas Edward et al.
Partner: UNT Libraries Government Documents Department
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Mechanical Properties of Zirconium and Zirconium-Uranium Alloys Containing Tin

Description: Abstract: "The mechanical properties of a large number of zirconium alloys have been investigated. These alloys include zirconium-tin and zirconium-tin-uranium. Tensile tests have been run on these alloys at room temperature, 500 F, and 600 F. Hot-hardness data have been obtained from room temperature to 1600 F, with particular emphasis on the hot-rolling range. Creep tests and fatigue tests have been run on a number of zirconium-tin alloys at 500 F."
Date: September 29, 1952
Creator: Schwope, A. D.; Muehlenkamp, G. T. & Chubb, Walston
Partner: UNT Libraries Government Documents Department
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Mechanical Properties of Zirconium and Zirconium-Uranium Alloys Containing Tin

Description: Abstract: "The mechanical properties of a large number of zirconium alloys have been investigated. These alloys include zirconium-tin and zirconium-tin-uranium. Tensile tests have been run on these alloys at room temperature, 500 F, and 600 F. Hot-hardness data have been obtained from room temperature to 1600 F, with particular emphasis on the hot-rolling range. Creep tests and fatigue tests have been run on a number of zirconium-tin alloys at 500 F."
Date: September 29, 1952
Creator: Schwope, A. D.; Muehlenkamp, G. T. & Chubb, Walston
Partner: UNT Libraries Government Documents Department
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Mechanical Properties of Iodide Zirconium Alloys

Description: Introduction: "The tensile properties, hot hardness, impact strength; and corrosion resistance of some arc-melted, iodide zirconium alloys have been determined. The alloys investigated include binary alloys of zirconium containing zero to five per cent tin, binary alloys of zirconium containing zero to 0.14 per cent nitrogen, and ternary alloys of zirconium containing tin and nitrogen, tin and uranium, and uranium and beryllium."
Date: November 1, 1952
Creator: Schwope, A. D. & Chubb, Walston
Partner: UNT Libraries Government Documents Department
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Mechanical Properties of Zirconium-Tin Alloys

Description: Abstract: "The mechanical properties and corrosion resistance of induction-melted, zirconium-tin alloys have been determined. The alloys investigated contained from zero to five per cent tin and up to 0.3% carbon. The zirconium used was United States Bureau of Mines sponge zirconium. The mechanical properties investigated include the tensile, hot-hardness, and impact properties."
Date: December 22, 1952
Creator: Schwope, A. D. & Chubb, Walston
Partner: UNT Libraries Government Documents Department
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Measurement of bulk longitudinal modulus and correction for edge effects

Description: Measurement of the bulk longitudinal modulus, M{sup *}, of rubbery polymers is a notoriously difficult task. Measurements are traditionally done through a fluid environment in methods that provide M{sup *} over only very narrow frequency ranges. An alternative approach, using a resonant test fixture is presented in this paper. A discussion of some physical limitations is developed. Among them are issues of repeatability and edge effects. A method of data analysis to address edge effects is also presented.
Date: December 31, 1993
Creator: Segalman, D. J. & Klenke, S. E.
Partner: UNT Libraries Government Documents Department
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Laboratory constitutive characterization of cellular concrete.

Description: To establish mechanical material properties of cellular concrete mixes, a series of quasi-static, compression and tension tests have been completed. This report summarizes the test methods, set-up, relevant observations, and results from the constitutive experimental efforts. Results from the uniaxial and triaxial compression tests established failure criteria for the cellular concrete in terms of stress invariants I{sub 1} and J{sub 2}. {radical}J{sub 2} (MPa) = 297.2 - 278.7 exp{sup -0.000455 I}{sub 1}{sup (MPa)} for the 90-pcf concrete {radical}J{sub 2} (MPa) = 211.4 - 204.2 exp {sup -0.000628 I}{sub 1}{sup (MPa)} for the 60-pcf concrete
Date: March 1, 2004
Creator: Hardy, Robert Douglas; Lee, Moo Yul & Bronowski, David R.
Partner: UNT Libraries Government Documents Department
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Chem-prep PZT 95/5 for neutron generator applications : effects of lead stoichiometry on the microstructure and mechanical properties of PZT 95/5.

Description: The microstructure and mechanical properties of niobium-modified lead zirconate titanate (PNZT) 95/5 ceramics, where 95/5 refers to the ratio of lead zirconate to lead titanate, were evaluated as a function of lead (Pb) stoichiometry. Chemically-prepared PNZT 95/5 is produced at Sandia National Laboratories by the Ceramics and Glass Processing Department (14154) for use as voltage elements in ferroelectric neutron generator power supplies. PNZT 95/5 was prepared according to the nominal formulation of Pb{sub 0.991+x}(Zr{sub 0.955}Ti{sub 0.045}){sub 0.982}Nb{sub 0.018}O{sub 3+x}, where x (-0.0274 {approx}< x {approx}< 0.0297) refers to the mole fraction of Pb and O that deviated from the stoichiometric value. The Pb concentrations were determined from calcined powders; no adjustments were made to Pb compositions due to weight loss during sintering. The microstructure (second phases, fracture mode and grain size) varied appreciably with Pb stoichiometry, whereas the mechanical properties (hardness, fracture toughness, strength and Weibull parameters) exhibited modest variation. Specimens deficient in Pb, 2.74% (x = -0.0274) and 2.15% (x = -0.02150), had a high area fraction of a zirconia (ZrO{sub 2}) second phase on the order of 0.02. As the Pb content in solid solution increased the ZrO{sub 2} content decreased; no ZrO{sub 2} was observed for the specimen containing 2.97% excess Pb (x = 0.0297). Over the range of Pb stoichiometry most specimens fractured predominately transgranularly; however, 2.97% Pb excess PNZT 95/5 fractured predominately intergranularly. No systematic changes in hardness or Weibull modulus were observed as a function of Pb content. Fracture toughness decreased slightly from 1.8 MPa{center_dot}m{sup 1/2} for Pb deficient specimens to 1.6 MPa{center_dot}m{sup 1/2} for specimens with excess Pb. Although there are microstructural differences with changes in Pb content, the mechanical properties did not vary substantially. However, the average failure stress and fracture toughness for PNZT 95/5 containing 2.97% excess Pb decreased slightly. It …
Date: September 1, 2004
Creator: Yang, Pin & Watson, Chad Samuel
Partner: UNT Libraries Government Documents Department
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Creep rupture properties of laves phase strengthened Fe--Ta--Cr--W and Fe-- Ta--Cr--W--Mo alloys

Description: A small addition of tungsten (0.5 at. percent) was shown to have an effect similar to that of molybdenum on the phase transformation characteristics of alloy Ta7Cr (with a nominal composition of 1 at. percent Ta, 7 at. percent Cr, balance Fe). The existence of time-temperature dependent transformation behavior in alloy Ta7Cr0.5W was confirmed. The effect of spheroidization time and temperature on creep strength was determined. In addition, effect of mechanical processing prior to aging, on creep strength was also determined. It was also shown that by suitable modifications of composition, the grain boundary film can be broken during the aging treatment without the use of spheroidization treatment. Microhardness, tensile and creep properties have been determined. Optical metallography and scanning electron microscopy have been used to follow the microstructural changes and mode of fracture. The creep rupture strength of alloy Ta7CrW alloy was found to be superior to many of the best commercially available ferritic alloys at 1200$sup 0$F. (21 fig., 8 tables) (auth)
Date: December 1, 1975
Creator: Singh, S.
Partner: UNT Libraries Government Documents Department
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Mechanical properties of thermal protection system materials.

Description: An experimental study was conducted to measure the mechanical properties of the Thermal Protection System (TPS) materials used for the Space Shuttle. Three types of TPS materials (LI-900, LI-2200, and FRCI-12) were tested in 'in-plane' and 'out-of-plane' orientations. Four types of quasi-static mechanical tests (uniaxial tension, uniaxial compression, uniaxial strain, and shear) were performed under low (10{sup -4} to 10{sup -3}/s) and intermediate (1 to 10/s) strain rate conditions. In addition, split Hopkinson pressure bar tests were conducted to obtain the strength of the materials under a relatively higher strain rate ({approx}10{sup 2} to 10{sup 3}/s) condition. In general, TPS materials have higher strength and higher Young's modulus when tested in 'in-plane' than in 'through-the-thickness' orientation under compressive (unconfined and confined) and tensile stress conditions. In both stress conditions, the strength of the material increases as the strain rate increases. The rate of increase in LI-900 is relatively small compared to those for the other two TPS materials tested in this study. But, the Young's modulus appears to be insensitive to the different strain rates applied. The FRCI-12 material, designed to replace the heavier LI-2200, showed higher strengths under tensile and shear stress conditions. But, under a compressive stress condition, LI-2200 showed higher strength than FRCI-12. As far as the modulus is concerned, LI-2200 has higher Young's modulus both in compression and in tension. The shear modulus of FRCI-12 and LI-2200 fell in the same range.
Date: June 1, 2005
Creator: Hardy, Robert Douglas; Bronowski, David R.; Lee, Moo Yul & Hofer, John H.
Partner: UNT Libraries Government Documents Department
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Fe--12Ni--4Co--2Mo--.05Ti alloy for use at 77$sup 0$K and below

Description: A variant of the maraging class of steels is proposed for application at 77$sup 0$K and below where a combination of very high strength and good toughness is required. The alloy has a composition of Fe-12Ni-4Co-2Mo-0.05Ti where low interstitial content. The as quenched and quenched and aged structures were completely martensitic with a prior austenitic grain size of 10 to 12 $mu$m. This structure had a Y.S. of 138.5 ksi and 154 ksi before and after aging respectively. All aging was done at 444$sup 0$C for 4 hours. The DBTT was shown to lie above 77$sup 0$K as measured by C/sub v/ testing. Based on dilatometric studies of the $alpha$ $Yields$ $gamma$ and $gamma$ $Yields$ $alpha$ transformation temperatures a cycling treatment consisting of reportedly heating to above the A/sub f/ temperature followed by a water quench was utilized to further reduce the prior $gamma$ grain size to approximately 4 to 6 $mu$m. The structure was completely martensitic and possessed a Y.S. of 151 ksi at 77$sup 0$K in the unaged condition with a Y.S./K/sub IC/ ratio of 1.9 while the aged structure showed a Y.S. of 162 ksi with a Y.S./K/sub IC/ ratio of 1.3. C/sub v/ testing showed the DBTT to lie between 77$sup 0$K and 4.2$sup 0$K. Further grain refinement was accomplished by a 2 phase decomposition procedure which resulted in a grain size of 1 to 2 $mu$m. The structure which contained decreasing amounts of austenite with temperature (3.0 percent at R.T. to 1.0 percent at 4.2$sup 0$K) showed the best combination of strength and ductility at 4.2$sup 0$K. A Y.S. of 205 ksi with a Y.S./K/sub IC/ ratio of 0.84 was achieved before aging. The aged structure was brittle at 4.2$sup 0$K with a Y.S. of 218 ksi and a Y.S./K/ sub IC/ ratio of 0.425. …
Date: October 1, 1975
Creator: Whitaker, B.W.
Partner: UNT Libraries Government Documents Department
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Strength testing of Ti-vapor-coated silicon nitride braze joints

Description: Sintered silicon nitride was vacuum brazed to itself at 1130{degree}C with a Au-25Ni-25Pd wt % filler metal. Wetting was obtained by coating the Si{sub 3}N{sub 4} surfaces with titanium prior to brazing by electron beam evaporation. The brazed joints were virtually free of porosity. Metallographic analysis showed that Ti reacted with the Si{sub 3}N{sub 4}, to form a TiN reaction layer during brazing. Small amounts of Si and Ti dissolved in the filler metal layers but they did not appear to influence the mechanical properties of the braze layer. Flexure bars were made from the brazed coupons and tested at room temperature, 600C, 700C, and 800C in air. At 700C and below, fracture of the test bars occurred in the Si{sub 3}N{sub 4}, either near the brazed surfaces or at some distance into the monolithic material. The measured strength of joint specimens decreased slightly with increasing test temperature, and generally exceeded the intrinsic braze filler metal strength in this temperature range. It was also found that lapping the Si{sub 3}N{sub 4}, prior to Ti coating reduced the number of near-surface flaws and produced joints with higher average strength and lower scatter than those left in a ground condition. Specimens tested at 800C had very low strengths, and this behavior was related to the microstructure at the brazed Si{sub 3}N{sub 4} surfaces.
Date: September 1, 1994
Creator: Santella, M. L.
Partner: UNT Libraries Government Documents Department
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Status of Initial Assessment of Physical and Mechanical Properties of Graphite Grades for NGNP Appkications

Description: Current candidate graphite grades for the core structures of NGNP include grades NBG-17, NBG-18, PCEA and IG-430. Both NBG-17 and NBG-18 are manufactured using pitch coke, and are vibrationally molded. These medium grain products are produced by SGL Carbon SAS (France). Tayo Tanso (Japan) produces IG-430 which is a petroleum coke, isostatically molded, nuclear grade graphite. And PCEA is a medium grain, extruded graphite produced by UCAR Carbon Co. (USA) from petroleum coke. An experimental program has been initiated to develop physical and mechanical properties data for these current candidate graphites. The results will be judged against the requirements for nuclear grade graphites set forth in ASTM standard D 7219-05 "Standard Specification for Isotropic and Near-isotropic Nuclear Graphites". Physical properties data including thermal conductivity and coefficient of thermal expansion, and mechanical properties data including tensile, compressive and flexural strengths will be obtained using the established test methods covered in D-7219 and ASTM C 781-02 "Standard Practice for Testing Graphite and Boronated Graphite Components for High-Temperature Gas-Cooled Nuclear Reactors". Various factors known to effect the properties of graphites will be investigated. These include specimen size, spatial location within a graphite billet, specimen orientation (ag and wg) within a billet, and billet-to-billet variations. The current status of the materials characterization program is reported herein. To date billets of the four graphite grades have been procured, and detailed cut up plans for obtaining the various specimens have been prepared. Particular attention has been given to the traceability of each specimen to its spatial location and orientation within a billet.
Date: December 1, 2011
Creator: Strizak, Joe P; Burchell, Timothy D & Windes, Will
Partner: UNT Libraries Government Documents Department
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