Showing papers on "Titanium published in 1971"

Grain refinement in aluminum alloyed with titanium and boron

Abstract: The aluminum corner of the ternary Al-B-Ti diagram was explored. A eutectic: Liq — Al + TiAl3 + (Al, Ti)B2 was found at approximately 0.05 wt pct Ti, 0.01 wt pct B; 659.5‡C. TiB2 and A1B2 form a continuous series of solid solutions, but no distinct ternary phase was found. The addition of boron to aluminum-titanium alloys expands the field of primary crystallization of TiAl3 toward lower titanium contents and steepens the liquidus. In equilibrium conditions, pronounced grain refinement is found only in alloys in which TiAl3 is primary and nucleates the aluminum solid solution before any other impurity can act. The peritectic reaction facilitates this priority but it is not necessary for grain refinement. Because of the low diffusivity of titanium and boron in aluminum, equilibrium is seldom attained and in commercial practice grain refinement by TiAl3 is found also outside its equilibrium field of primary crystallization.

Behavior of hydrogen in α-phase Ti-Al alloys

Abstract: The solubility of hydrogen in titanium and various Ti-Al alloys is measured by a resistometric technique and by direct observation in the electron microscope. Aluminum is shown to increase the solubility of hydrogen in titanium and a thermodynamic argument is used to demonstrate that this increased solubility can be due to the self-stresses around the hydride introduced as a result of the increase in volume accompanying the Ti+H→TiH transformation. The hysteresis in resistivity as a function of temperature for the high aluminum alloys is interpreted as being due to the irreversible work done in plastic deformation of the matrix around the hydride. particles and is necessary because maximum elastic strains in the matrix are insufficient to accommodate the deformation induced by the transformation.

Chemical vapor deposition coatings on titanium

Abstract: A process for coating titanium-containing substrates with a dense, adherent, chemically vapor deposited coating by initially effecting a pro-tective, adhesion-promoting, intermediate layer on the titanium surface and subsequently depositing from the vapor phase a metal nitride, carbide, or carbonitride coating on the intermediate film. For example, a titanium article may be initially nitrided to provide a titanium nitride protective layer and titanium nitride, titanium carbide, or titanium carbonitride may subsequently be deposited from the vapor phase onto this film to provide a dense, adherent, protective coating on the titanium article. The barrier layer serves to pro-mote adhesion between the titanium substrate and the final overlay and to prevent reaction between the substrate and such a reaction ingredient as titanium tetrachloride, which is a preferred constituent for supplying titanium in the titanium carbide, nitride, or carbonitride final coating.

Porous titanium surgical implant materials

Abstract: Porous pure titanium and titanium-6% aluminum-4% vanadium alloy materials, made by several powder metallurgy techniques, have been studied for potential use as surgical implant materials. Tissue ingrowth into open porosity and favorable physical properties have been found. Tensile strength and ductility data are presented as a function of density. Microscopic observations include scanning electron microscope pictures of the surface of specimens prior to implantation in animals, photomicrographs of the internal pore structure, macrophotographs of surfaces before and after polishing, and histological photomicrographs illustrating the nature of the tissue ingrowth found.

New crystallographic shear families derived from the rutile structure, and the possibility of continuous ordered solid solution

Abstract: A number of new families of titanium and mixed titanium plus chromium oxides has been discovered, their structures all being derived from the rutile type by crystallographic shear. Different famili...

Strain-rate and strain-rate-history effects in several metals in torsion

Abstract: A machine for testing thin-walled tubes in torsion at shear-strain rates up to 25/sec is described Results of constant and variable-strain-rate tests are presented for 1100-0 aluminum, AISI 1020 steel, and 50-A titanium Results indicate that 1100-0 aluminum is very slightly strain-rate sensitive, but steel and titanium are noticeably sensitive to both strain rate and strain-rate history Variable-rate tests show that subsequent dynamic loading on a statically prestrained specimen causes an increase in the flow stress in steel and a decrease in the flow stress in titanium

Concerning the Critical Pitting Potential

Abstract: The critical pitting potential, defined as the least positive potential at which pits can be grown, may be that potential at which the metal salt of the aggressive ion in solution is in equilibrium with the metal oxide. Such an equilibrium may be achieved when the activity of the anion in the pit has been increased by the potential difference between the inside and outside of the pit. The theory successfully predicts the critical pitting potentials for aluminum, magnesium, iron, and nickel, but fails for zirconium, titanium, and tantalum.

Microstructural analysis of neutron irradiated titanium and rhenium

Abstract: The defect structure in α-titanium and rhenium irradiated with neutrons at 04T m (T m = absolute melting temperature) has been analyzed using transmission electron microscopy In rhenium, the vacancies agglomerate into voids whereas in titanium, vacancy dislocation loops lying on the prism planes are the only vacancy type defects observed In both metals, dislocation segments and network fragments are the main evidence of interstitial type defects The presence of dislocation loops rather than voids in titanium irradiated at this temperature is an anamalous result when compared to results on other similarly irradiated pure metals Possible explanations for the preferential formation of loops rather than voids in the titanium are discussed

Effect of gamma-gamma prime mismatch, volume fraction gamma prime, and gamma prime morphology on elevated temperature properties of Ni, 20 Cr, 5.5 Mo, Ti, Al alloys

Abstract: This study was designed to provide a critical test for the postulate that the mismatch between the lattices of austenite (γ) and the age-hardening gamma-prime (γ′) precipitates and the resultant coherency strains have a significant influence on the elevated temperature, particularly stress rupture, properties of a nickel-base superalloy. Two experimental alloys with a base analysis of Ni, 20 Cr, 5.5 Mo were designed with variable titanium and aluminum additions. To discern the effect of mismatch, an alloy without molybdenum was also experimented with. By manipulating the mismatch and volume fraction γ′ by heat treatment and chemistry, it was shown that a lower γ-γ′ mismatch indeed is beneficial to stress rupture life. Importance of volume fraction γ′ on this elevated temperature was also established.

Titanium as a luminescence centre in thermoluminescent lithium fluoride

Abstract: Single crystals have been grown based on optical quality lithium fluoride with the addition of magnesium and titanium. The content and distribution of titanium has been determined by x-ray fluorescence analysis and related to the intensity of an optical absorption band near 200 nm. The variation of thermoluminescence intensity within each crystal has been studied and related to titanium distribution.

Method of brazing

Abstract: A method of brazing together bodies composed either of dense self-bonded silicon carbide containing free silicon or dense carbon using a brazing material consisting of an alloy of silicon with one or more metals, in particular germanium, iron, gold, nickel, palladium, platinum, chromium, titanium, which alloy contains at least 5 atomic per cent of silicon, has a melting temperature not higher than 1400 DEG C, has thermal expansion characteristics matching those of the bodies to be brazed together, and in the molten state is capable of wetting the surfaces of the bodies. The method is especially suitable for bracing silicon carbide caps to silicon carbide nuclear fuel element containers.

The importance of mechanical twinning in the stress-strain behavior of swaged high purity fine-grained titanium below 424°K

Abstract: Zone-refined iodide titanium specimens, swaged and annealed at different temperatures to give a range of grain sizes from 2.4 to 22 μ, were deformed to fracture between 77° and 424°K. A metallographic study of the fractured specimens revealed that mechanical twinning is an important factor in the plastic deformation of this grade of titanium at subambient temperatures. In all cases, the volume fraction of twins increased steadily with strain as well as with decreasing deformation temperature. At 77°K and at a grain size of 22 μ, the twin volume fraction was greater than 0.5 at a strain of 0.5. Furthermore, each of the 77°K stress-strain curves showed a linear work-hardening character with an associated high ductility similar to that originally reported by Wasilewski for commercial purity titanium. The nearly linear stress-strain curve in this latter case has been rationalized earlier in terms of deformation twinning. The present results are in good agreement with this point of view.

Catalyst and catalytic process

Abstract: A CATALYST CONTAINING CHROMIUM OXIDE SUPPORTED ON A DIFFICULTY REDUCIBLE CARRIER AS ITS MAJOR COMPONENT AND ALSO INCLUDING METAL OF THE CLASS CONSISTING OF TITANIUM, BORON, VANADIUM AND MIXTURES OF THESE IN WHICH THE CATALYST IS PARTICULARLY USEFUL FOR POLYMERIZING OLEFINS AND PARTICULARLY THOSE OF FROM 2 TO 8 CARBON ATOMS SO AS TO PREDETERMINE THE STRUCTURE, COMPOSITION, PHYSICAL AND CHEMICAL PROPERTIES AND USES AND APPLICATIONS OF THE RESULTING POLYMERS BY THE COMPONENTS OF THE CATALYST, WITH THE RESULT THAT THE POLYMER DESIRED IS PRODUCED IN THE REACTOR RATHER THAN BY POST-TREATMENT OF THE POLYMER OR BLENDING OF TWO OR MORE POLYMERS WITH DIFFERENT PROPERTIES IN AN ATTEMPT TO ACHIEVE A BLEND OF THE DESIRED PROPERTIES. THE DISCLOSURE ALSO INCLUDES THE METHOD OF POLYMERIZING AT LEAST ONE OLEFIN BY A PARTICLE FORM OR SLURRY PROCESS UTILIZING THE NEW CATALYST WITH THE POLYMERIZATION TAKING PLACE IN AN INERT DILUENT IN WHICH THE RESULTING POLYMER IS SUBSTANTIALLY INSOLUBLE AT THE TEMPERATURE AND PRESSURE OF POLYMERIZATION. THE NEW CATALYSTS CAN ALSO BE USED IN SOLUTION FORM POLYMERIZATION. THE CATALYST INCLUDES CHROMIUM OXIDE PLUS AN OXYGENATED METAL COMPOUND OF TITANIUM, BORON OR VANADIUM OR COMBINATIONS OF THESE. EXAMPLES OF SUCH CATALYSTS ARE CHROMIUM OXIDE PLUS TITANIUM, CHROMIUM OXIDE PLUS BORON, CHROMIUM OXIDE PLUS VANADIUM, CHROMIUM OXIDE PLUS TITANIUM AND BORON AND CHROMIUM OXIDE PLUS TITANIUM AND VANADIUM. IN EACH OF THESE THE TITANIUM, BORON AND VANADIUM ARE OXYGENATED AND PREFERABLY PREPARED BY TREATING THE ORGANIC COMPOUNDS, AND SPECIFICALLY ESTERS, OF THESE METALS WITH OXYGEN.

Processing for the high strength alpha-beta titanium alloys

Abstract: A PROCESS FOR IMPROVING THE TOUGHNESS AND PROPERTY UNIFORMITY OF THE HIGH STRENGTH ALPHA-BETA TITANIUM FORGED ALLOYS BY A SPECIFIC HEAT TREATMENT SCHEDULE WHICH INCLUDES A SHORT ISOTHERMAL TRANSFORMATION HEAT TREATMENT STEP LOW IN THE ALPHA-BETA REGION SUBSEQUENT TO SOLUTIONING TREATMENT HIGH IN THE ALPHA-BETA REGION.

Nickel-iron base alloys and heat treatment therefor

Abstract: PRECIPITATION HARDENED NICKEL-IRON BASE ALLOYS WITH OR WITHOUT CHROMIUM AND COBALT CONTAINING COLUMBIUM, TITANIUM AND ALUMINUM ARE PROVIDED BY HEAT TREATMENT WITH A UNIQUE COMBINATION OF ROOM TEMPERATURE AND ELEVATED TEMPERATURE PROPERTIES.

Method for producing a master alloy for use in aluminum casting processes

Abstract: A method for producing a master alloy for use in aluminum casting processes in which an aluminum melt containing 0.02-6 percent by weight titanium and 0.01-2 percent by weight boron is produced under conditions under which the boron is bound to titanium in the form of titanium diboride, whereafter the melt containing titanium diboride is held under agitation at a temperature ranging from the melting point of the material to 900* C for a period of at least 15 minutes and at most 9 hours.

The mechanisms of grain refinement in dilute aluminum alloys

Abstract: The contribution of the peritectic reaction in producing grain refinement in aluminum alloys has been studied in three binary aluminum systems. It appears that titanium has a unique effect compared with zirconium or chromium; there is evidence of a refinement mechanism associated with the peritectic reaction in Al−Ti alloys which was not observed in the other two systems. Additions of boron to Al−Ti and Al−Zr alloys emphasizes the difference in effect of these two transition elements as grain refiners. The significance of the present work is discussed with reference to conflicts apparent in earlier experimental data.

Method of producing valve metal electrode with valve metal oxide semiconductive coating having a chlorine discharge catalyst in said coating

Abstract: 1. THE METHOD OF PRODUCING AN ELECTRODE OF A VALVE METAL BASE FROM THE GROUP CONSISTING OF TITANIUM AND TANTALUM WHICH COMPRISES APPLYING A COATING MIXTURE IN LIQUID FORM TO SAID VALVE METAL BASE, WHICH ON HEATING FORMS AN OXIDE LAYER ON SAID BASE, 39.2% TO 78% OF WHICH COMPRISES AN OXIDE OF TITANIUM, 6.4% TO 47.45% OF WHICH COMPRISES AN OXIDE OF A PLATINUM GROUP METAL AND 1% TO 17.7% OF WHICH FORMS AN OXIDE OF A DOPING METAL FROM THE GROUP CONSISTING OF TIN, VANADIUM, LANTHANUM, COBALT, AND MIXTURES THEREOF, THE SAID PERCENTAGES BEING BASED UPON THE WEIGHT OF THE METALS IN SAID OXIDES, APPLYING SAID COATING IN SEVERAL SEPARATE LAYERS AND HEATING THE COATING ON THE VALVE METAL BASE BETWEEN THE APPLICATION OF EACH LAYER.