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Tensile Properties of Yttrium-Titanium and Yttrium-Zirconium Alloys

Description: Complete series of yttrium-titanium and yttrium-zirconium alloys was tested in tension at room temperature. Ultimate tensile strength, yield strength, and reduction in area data are reported for the alloys. Yield point phenomena were encountered in both alloy systems. (auth)
Date: December 1, 1960
Creator: Bare, D. W.; Gibson, E. D. & Carlson, O. N.
Partner: UNT Libraries Government Documents Department

Aluminum powder metallurgy processing

Description: The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.
Date: February 12, 1999
Creator: Flumerfelt, J.F.
Partner: UNT Libraries Government Documents Department


Description: The solid solubility of yttrium in iron-20 to 40 wt.% chromium alloys was determined by metallographic techniques and found to be extremely small. At 1320 deg C, the maximum solubility is about 0.12 wt. a yttrium. Study of iron- rich alloys of the iron-yttrium system shows that the compound YFe/sub 5/ exists. A eutectic occurs between iron and YFe/sub 5/ at 1257 deg C. The constitution of iron - 20 to 40 wt.% chromium-yttrium alloys ccntaining less than 6 wt.% yttrium was studied between 1250 and 600 deg C. It was found that, upon exceeding the solubility limit, YFe/sub 5/ is formed and cccurs in conjunction with alpha iron - chromium. At about 900 deg C and above 615 deg C, if more than 6 wt.% yttrium is present in the iron-35 wt.% chromium alloy and more than 3 wt. % in iron-40 wt.% chromium alloy, YFe/sub 4/ forms to give a three-phase field of alpha plus YFe/sub 5/ plus YFe/sub 4/. The upper yttrium limit of this phase field was not determined. At 815 deg C, sigma phase forms in the iron - chromium system and comes into equilibrium with YFe/sub 5/. (auth)
Date: October 20, 1959
Creator: Farkas, M.S. & Bauer, A.A.
Partner: UNT Libraries Government Documents Department

Effects of High Neutron and Gamma Fluxes on the Transmission Characteristics of Some Optical Glasses

Description: The design of the Sandia Engineering Reactor Facility (SERF) presented a unique problem of finding a way to view the virtually unshielded 5 Mw reactor during operation. It was determined that periscope viewing was most feasible. The front optical elements of the periscope must withstand a total integrated radiation dose of 3 x 10/sup 9/ of gammas, and 1.4 x 10/sup 7/ n/cm/sup 2/, without excessive transmission losses. A program started to study the effects of radiation at such rates and total doses on the transmission characteristics of available optical glasses is described. Curves plotted from the study are presented to show graphically the results of irradiation on these optical glasses. (W.D.M.)
Date: November 1, 1959
Creator: Colp, J. L. & Woodall, H. N.
Partner: UNT Libraries Government Documents Department

Transient oxide phases and scale strain in MCrAlY : a light scattering study.

Description: We have used Raman ''fingerprinting'' to investigate the temperature dependence of the transient oxide phases in the scale formed on MCrAl and MCrAlY (M=Ni,Co) in the temperature range 300 to 1200 C. In particular, by extending our Raman spectra to include second order scattering, we are able to track the evolution of NiO in the scales. We find that the inclusion of Y, while improving scale adhesion, inhibits the formation of Co oxide. We have also exploited the strain dependence of ruby fluorescence to extract the residual strain in the oxide scale.
Date: June 3, 1998
Creator: Renusch, D.
Partner: UNT Libraries Government Documents Department

Significance of Experimental Procedures on the Hot Corrosion Behavior of Nickel-Base Alloys Under Cyclic Conditions

Description: A simplified test procedure was established to assess the hot corrosion behavior of MCrAlY-type nickel-base alloys under the influence of molten sodium sulfate as well as sodium sulfate/potassium sulfate salt mixtures. Salt coated specimens were exposed to lh thermal cycles at 950°C in flowing oxygen for up to 500 cycles. Mass change data of the specimens revealed a significant dependence of the corrosion attack not only, as expected, on the average contaminant flux rate, but also on the initial amount of salt deposited during each recoating cycle. Furthermore, deposit removal before salt recoating was found to markedly influence the corrosion attack of the alloys. This was related to changes in salt chemistry by the dissolution of elements such as Cr from the alloy which shifted the basicity of the salt and thus affected the extent of attack. Substituting Na for K in sodium sulfate/potassium sulfate salt mixtures enerally resulted in a decreased attack. Although the high K-containing salts still caused significant attack typical of Type-I hot corrosion, the overall degration was much less than for sodium sulfate alone.
Date: February 25, 1999
Creator: Leyens, C.; Pint, B.A.; Tortorelli, P.F. & Wright, I.G.
Partner: UNT Libraries Government Documents Department

Rare Earth Thermoelectrics

Description: The author reviews the thermoelectric properties of metallic compounds which contain rare-earth atoms. They are the group of metals with the largest value ever reported of the Seebeck coefficient. An increase by 50% of the Seebeck would make these compounds useful for thermoelectric devices. The largest Seebeck coefficient is found for compounds of cerium (e.g., CePd{sub 3}) and ytterbium (e.g., YbAl{sub 3}). Theoretical predictions are in agreement with the maximum observed Seebeck. The author discusses the theoretical model which has been used to calculate the Seebeck coefficient. He is solving this model for other configurations (4f){sup n} of rare-earth ground states.
Date: September 1, 1997
Creator: Mahan, G. D.
Partner: UNT Libraries Government Documents Department

Studies on the Optimization of Deformation Processed Metal Metal Matrix Composites

Description: A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New and novel alloying procedures were investigated to extend the range of production methods available for these material. These studies focused on the use of High Pressure Gas Atomization and the development of new containment technologies for the liquid alloy. This allowed the production of alloys with a much more refined starting microstructure and lower contamination than available by other methods. The knowledge gained in the previous studies was used to develop two completely new families of deformation processed metal metal matrix composites. These composites are based on immissible alloys with yttrium and magnesium matrices and refractory metal reinforcement. This work extends the physical property range available in deformation processed metal metal matrix composites. Additionally, it also represents new ways to apply these metals in engineering applications.
Date: January 4, 1994
Creator: Ellis, Tim W.
Partner: UNT Libraries Government Documents Department

Low-temperature specific heat of YMn{sub 2} in the paramagnetic and antiferromagnetic phases

Description: The low-temperature specific heat of YMn{sub 2} has been measured at applied pressures of 0 to 7.7 kbar. A paramagnetic state is stabilized for moderate values of the applied pressure (of the order of 1.6 kbar). A large linear term in the specific heat, which decreases regularly with increasing pressure, is observed in this phase. It is ascribed to giant spin fluctuations associated with a magnetic-non magnetic instability and a strong geometrical spin frustration.
Date: July 1, 1992
Creator: Fisher, R. A.; Emerson, J. P.; Phillips, N. E.; Ballou, R. & Lelievre-Berna, E.
Partner: UNT Libraries Government Documents Department


Description: The development and operation of the Los Alamos Molten Plutonium Reactor Experiments are described. The development and compatibility of iron-- plutonium and cerium-cobalt-- plutonium alloy fuels are evaluated. The fabrication and testing of the liquid sodiam loop are summarized. The phase studies of plutoniam alloys containing neodymium, scandium, yttrium, praseodymium, and cerium-- cobalt mixtures are reported. (N.W.R.)
Date: December 1, 1963
Partner: UNT Libraries Government Documents Department


Description: Some 53 high-purity binary tantalum-base alloys were prepared and evaluated as candidate materials of construc tion for the Los Alamos Molten Plutonium Reactor Experiment. Preliminary data indicate that good resistance to attack by the fuels can be obtained by alloying tantalum. Alloys containing additions of rhenium and tungsten showed good corrosion resistance in polythermal (1352 to 1022 deg F) tilting-furnace exposures. Tantalum--yttrium alloys also displayed good corrosion resistance, even though the yttrium apparently was lost during arc melting. Most of the alloys, including those which showed good corrosion resistance, were amenable to arc melting and casting and fabrication at room temperature. (auth)
Date: February 14, 1961
Creator: Drennen, D.C.; Langston, M.E.; Slunder, C.J.; Dunleavy, J.G. & Hall, A.M.
Partner: UNT Libraries Government Documents Department

Effects of Yttrium on the Fabrication and Tensile Properties of Two Modified Stainless Alloys

Description: Alloys containing 55 wt.% iron--22 wt.% nickel-- 17 wt.% chromium--2.5 wt.% molybdenum- 1.0 wt.% niobium-0.03 wt.% carbon-- 0.5 wt.% manganese-- 0.5 wt.% silicon with nominal additions of from 0 to 1.5 wt.% yttrium, and 36 wt.% iron-37 wt.% nickel--18 wt.% chromium--2.5 wt.% molvbdenum- 1.5 wt.% niobium-- 1.0 wt.% aluminum-0.05 wt.% carbon--0.5 wt.% manganese-- 0.5 wt.% silicon with nominal additions of from 0 to 2.0 wt.% yttrium, were prepared by vacuum- induction melting. Alloys containing 55 wt.% iron were successfully forged in air at 1900 deg F, rolled at 1850 deg F to 0.060-in. sheet and cold rolled to 0.015in. sheet. Fabrication of alloys containing 36 wt.% iron with more than 0.5 wt.% yttrium was unsuccessful. Addition of yttrium had relatively no effect on the yield and ultimate strength from room temperature to 1850 deg F. The ductility of fabricable alloys studied was increased at elevated temperatures by increasing yttrium contents. The greatest increase in ductility occurred at 1.5 wt.% yttrium. (auth)
Date: February 24, 1960
Creator: DeMastry, J. A.; Shober, F. R. & Dickerson, R. F.
Partner: UNT Libraries Government Documents Department


Description: The beryllium compounds NbBe/sub 12/, YBe/sub 13/, and ZrBe/sub 12/ were prepared by arc melting. Some beryllium was lost in this operation but sound ingots were obtained. The hardness, density, metallographic structure, x-ray structure, and oxidation resistance in air of each ingot were determined. The zirconium compound apparently had a tetragonal structure corresponding to ZrBe/ sub 12/ and a hardness of 790 Knoop and a density of 2.94 g per cm/sup 3/. The yttrium compound had a cubic structure corresponding to YBe/sub 13/ and a hardness of 570 Knoop and a density of 2.57 g per cm/sup 3/. The niobium compound had a tetragonal structure corresponding to NbBe/sub 12/ and a hardness of 1100 Knoop and a density of 3.14 g pre cm/sup 3/. The zirconium alloy was most difficult to prepare and crumbled at 700 deg C during oxidation testing. The niobium and yttrium alloys were both relatively easy to prepare and both were highly resistant to oxidation at 1300 deg C. The niobium alloy had the most satisfactory behavior in all respects and appears most promising for further development. (auth)
Date: March 1, 1959
Creator: Chubb, W. & Dickerson, R.F.
Partner: UNT Libraries Government Documents Department

Characterization of mechanical properties of aluminized coatings in advanced gas turbine blades using a small punch method

Description: Advanced technologies of superalloy casting and coatings enable one to enhance the performance of combined cycle gas turbines for electric power generation by increasing the firing temperature. This paper describes examination of the microstructure/composition and mechanical properties (22--950 C) in aluminized CoCrAlY coatings of advanced gas turbine blades using scanning Auger microprobe and a small punch (SP) testing method. Aluminized coatings consisted of layered structure divided into four regimes: (1) Al enriched and Cr depleted region, (2) Al and Cr graded region, (3) fine grained microstructure with a mixture of Al and Cr enriched phases and (4) Ni/Co interdiffusion zone adjacent to the interface. SP specimens were prepared in order that the specimen surface would be located in the various coating regions. SP tests indicated strong dependence of the fracture properties on the various coatings regimes. Coatings 1 and 2 with very high microhardness showed much easier formation of brittle cracks in a wide temperature range, compared to coatings 3 and 4 although the coating 2 had ductility improvement at 950 C. The coating 3 had lower room temperature ductility than the coating 4. However, the ductility in the coating 3 exceeded that in the region 4 above 730 C due to a precipitous ductility increase. The integrity of aluminized coatings while in-service is discussed in light of the variation of the low cycle fatigue life as well as the ductility in the layered structure.
Date: April 1, 1997
Creator: Sugita, Y.; Ito, M.; Sakurai, S.; Bloomer, T.E. & Kameda, J.
Partner: UNT Libraries Government Documents Department

Evaluation of Oxide Dispersion Strengthened (ODS) molybdenum alloys

Description: A series of fourteen (14) novel high-strength molybdenum alloy compositions containing a dispersion of very fine (< 1 {mu}m diameter) oxide particles were consolidated using two proprietary powder metallurgy techniques. The developmental compositions were evaluated to determine the microstructural stability and mechanical properties from cryogenic (-148{degrees}F) to elevated temperatures (4000{degrees}F) for material in the as-swaged (>98% cold work) condition and for as-swaged material in the heat treated condition. Extremely fine oxide particle sizes (<1000 {Angstrom}) were observed by Transmission Electron Microscopy (TEM) for a number of the experimental compositions in the as-swaged condition. A one hour recrystallization temperature as high as 3990{degrees}F was measured and a ductile-to-brittle transition temperature as low as {approximately}58{degrees}F for material in the recrystallized condition was determined. The preliminary results support the alloy design concept feasibility.
Date: December 31, 1995
Creator: Bianco, R. & Buckman, R.W. Jr.
Partner: UNT Libraries Government Documents Department

Isothermal and cyclic oxidation of an air plasma-sprayed thermal barrier coating system

Description: Thermogravimetric methods for evaluating bond coat oxidation in plasma-sprayed thermal barrier coating (TBC) systems were assessed by high-temperature testing of TBC systems with air plasma-sprayed (APS) Ni-22Cr-10Al-1Y bond coatings and yttria-stabilized zirconia top coatings. High-mass thermogravimetric analysis (at 1150{sup degrees}C) was used to measure bond coat oxidation kinetics. Furnace cycling was used to evaluate APS TBC durability. This paper describes the experimental methods and relative oxidation kinetics of the various specimen types. Characterization of the APS TBCs and their reaction products is discussed.
Date: August 1, 1996
Creator: Haynes, J.A.; Ferber, M.K.; Porter, W.D. & Rigney, E.D.
Partner: UNT Libraries Government Documents Department