Showing papers on "Alloy published in 1970"

Heat recoverable alloy

Abstract: An alloy capable of having the property of heat recoverability imparted thereto comprising 49.1 to 50.2 atomic percent of titanium, 2.1 to 4.7 atomic percent of iron and the remainder nickel.

High-temperature oxidation of alloys

Abstract: Some recent developments in the understanding of the oxidation of alloys at elevated temperatures are reviewed, with special reference to binary and ternary alloys upon which many commercial materials are based. Following an initial classification of alloy systems, certain basic principles and their limitations are considered, including factors determining whether an alloy displays surface scaling only, internal oxidation only, or both phenomena; the mode of distribution of cations in an oxide solid solution growing on an alloy; and doping and the Wagner-Hauffe rules. Previous alloy oxidation theory has concerned itself principally with steady-state oxidation but, in practice, behavior of the oxidizing sample in approaching the steady state, both upon initial exposure to the environment and after scale spalling induced isothermally or during thermal cycling, is often as important. Such behavior is illustrated in terms of scale establishment and with respect to compositional changes in the subjacent alloy, the importance of certain alloy and oxide properties being emphasized. After further brief consideration of steady-state scaling, the causes and consequences of breakaway oxidation are presented. The role of major and minor concentrations of third elements on scaling behavior is discussed. The paper concludes with brief reference to situations not considered in detail and with aspects requiring further study.

The transient oxidation of alloys

Abstract: The pre-steady-state oxidation of a wide range of binary alloys of practical importance, in 1 atm oxygen at 600° C, is discussed in terms of the main determining parameters, namely the free energies of formation and growth rates of the component and complex oxides, the bulk alloy composition, the alloy interdiffusion coefficient, the oxygen solubility and diffusivity in the alloy, and effects such as epitaxy. Schematic diagrams are used to illustrate the morphology and structure of the films, as revealed by electron microscopy and diffraction. After tabulation of the sparse, and often apparently unreliable, fundamental parameters, a comparison is made within each of the following groups of alloys: (1) Fe-Cr, Ni-Cr, and Co-Cr alloys, in which the less noble metal is the same and the noble metal is varied, there being composition ranges in which noble metal oxide and less noble metal oxide respectively predominate but in which the oxides are partially miscible or react. (2) Ni-Al, Ni-Cr, Ni-Si, Ni-Mn, and Ni-Co alloys, in which the noble metal is the same, the less noble metals have a wide range of affinities for oxygen and oxidation rates, and the oxide phases produced include solid solutions, largely immiscible simple oxides, and complex oxides. (3) Cu-Ni, Cu-Zn, and Cu-Al alloys, in which the noble metal is the same and the less noble metal is varied, the oxides being largely immiscible.

High temperature oxidation resistant coating alloy

Abstract: A coating alloy for the gas turbine engine super-alloys is described which consists primarily of nickel, aluminum and a reactive metal such as yttrium, particularly at the composition, by weight, 14-30 percent aluminum, 0.01-0.5 percent reactive metal balance nickel. A preferred embodiment also includes 15-45 weight percent chromium.

Factors influencing the formation of silver-rich solid solutions in rare- earth--silver alloy systems.

Abstract: The solid solubilities of all of the naturally occurring rare-earth metals in silver have been determined by using the X-ray parametric method. The solubilities range from 0.01 to 0.02 at. pct for Eu to 10.5 at. pct for Sc. The stoichiometries of the silver-rich compounds and some of their crystal structures were determined. The silver-rich compounds found in this study are: RAg5(La, Ce, Pr, Eu, and Yb), RAg4(Lu and Sc), R14Ag5l(La to Sm, Gd to Er, Yb, and Y) and TmAg3. The silver/silver-rich compound eutectic temperatures were also determined. Analysis of these data indicates that several factors in addition to the Hume-Rothery criteria influence the formation and extent of solid solutions. These include the mutual adjustment of size and electronegativity of the solvent and solute if the pure metal size differences are less than a critical value of 22 to 25 pct, the composition of the first solvent-rich compound, and the lattice rigidity of the solvent.

Decomposition of the metastable beta phase in the all-beta alloy Ti-13V-11Cr-3Al

Abstract: The phase transformations which occur in the all-β titanium alloy Ti-13V-llCr-3Al at temperatures below ∼ 500°C have been studied by transmission electron microscopy, X-ray diffraction, and electrical resistivity techniques. The decomposition of the metastable β phase has been found to proceed through a transition reaction leading to the formation of two bcc phases rather than through the precipitation of the ω phase as has been previously reported. An interpretation of the observed decomposition sequence, based on thermodynamic reasoning, is presented. The decomposition characteristics of the Ti-13V-llCr-3Al alloy have been compared with those of a Ti-13V-llCr alloy to determine the influence of aluminum on the transformation behavior.

Sintering steel-bonded carbide hard alloy

Abstract: A sintered alloy comprising a carbide of preferably titanium and a steel matrix of an alloy steel containing chromium, molybdenum, copper and vanadium as alloying elements provide high temperature hardness and wear resistance. Preferred alloys contain 0.8 to 1.9% by weight of manganese and up to 80% by weight of carbide.

Copper plating on zinc and its alloys

Abstract: Production of a uniform, continuous corrosion resistant bonded copper coating on a zinc or zinc alloy body, by a process which comprises contacting the zinc or zinc alloy body with an electroless copper plating composition or solution consisting essentially of a soluble copper salt, e.g., copper sulfate, a complexing agent, e.g., citric acid, and a reducing agent, e.g., sodium hypophosphite. The resulting zinc or zinc alloy body can then be contacted with a copper electroplating bath, and according to one embodiment the resulting copper plated zinc or zinc alloy body is then treated in a nickel electroplating solution, followed by treatment in a chromic acid electroplating solution, to provide a corrosion resistant bright attractive metal coating on the zinc or zinc alloy body. The above noted novel electroless copper plating composition, and the zinc or zinc alloy article coated with an electroless copper plating.

The Transient Oxidation of Fe‐Cr and Ni‐Cr Alloys

Abstract: The early stages of oxidation of Fe‐Cr and Ni‐Cr alloys, containing respectively nominally 5, 10, 15, and 30 a/o Cr, in 1 atm oxygen at 600°C have been studied by transmission electron microscopy of stripped films and by electron diffraction. Substantial amounts of iron and nickel oxides, respectively, are produced on all alloys before steady‐state, healing, chromium‐containing oxide layers are developed. This occurs more rapidly and more completely as the alloy chromium content is increased. For dilute Fe‐Cr and very dilute Ni‐Cr alloys, grain and subgrain boundaries and other substructural defects of the alloy are covered by thicker oxide. This is due either to their efficiency as cation vacancy sinks or to more local diffusional paths in the oxide above them. Conversely, for alloys richer in chromium (up to 30%), healing is most rapid in these locations due to rapid chromium diffusion to the alloy/oxide interface, leading to thin oxide above the defects. The tendency of rapidly growing iron oxides to overgrow the chromium‐containing oxides, and also to undermine them by encroaching on the alloy, is countered by the rapid development of a general healing layer of for the dilute Fe‐Cr alloys and for the concentrated alloys. probably does not form a healing layer for dilute Ni‐Cr alloys and the completion of a healing layer is slower than for Fe‐Cr alloys. This is largely due to the lower alloy interdiffusion coefficient. However, the slow growth of limits overgrowth and scale encroachment. healing is eventually approached by dense internal oxide formation, resulting partly from the relatively high solubility of oxygen in Ni‐Cr alloys.

Rate of crystallization of an amorphous FePC alloy

Abstract: An alloy containing iron, phosphorus and carbon in the atomic concentrations corresponding to Fe75P15C10 can be obtained in the amorphous state by rapid quenching from the liquid state. The transformation of this alloy from the amorphous to the equilibrium crystalline state has been studied by thermal analysis, X-ray and electrical resistivity. At rates of heating above approximately 320°C/min, the alloy transforms very rapidly into a microcrystalline structure with an average crystal size of about 300A. At slightly lower rates (about 100°C/min) it is possible to stop the massive crystallization and microcrystalline clusters of metastable phases imbedded in an amorphous matrix are present. At a relatively low rate of heating of 1°C/min, crystallization starts around 375°C, but has a sudden increase in the range of 420 to 440°C. This increase in crystallinity is reflected in the electrical resistivity which also shows a sharp drop within the same temperature range. Before this massive crystallization takes place, the electrical resistivity increases slowly with temperature. This behavior has been observed previously in a number of amorphous alloys. In the amorphous FePC alloy, this increase in resistivity is not a reversible phenomenon, and the results of the present investigation suggest that it is due to additional scattering of the conduction electrons by very small clusters of crystalline phases, about 50A in size.

Process of forming protective coatings on metallic surfaces by spraying a combination of powders of a metal alloy,chromium and a ceramic oxide

Abstract: DESCRIBED IS A PROTECTIVE TREATMENT AS ANTIOXIDANT BARRIER AND AS HEAT BARRIER FOR FERROUS AND NON-FERROUS METALLIC SURFCES. THE TREATMENT COMPRISES SPRAY DEPOSITING IN A MOLTEN STATE A COMBINATION OF POWDERS OF THREE COMPONENTS COMPRISING A METAL ALLOY A, A METAL B, AND A METAL OXIDE C ONTO THE BASE SURFACE.

Titanium alloying in theory and practice

Abstract: The Ti-Al-Sn-Zr system is surveyed with emphasis on 1000°F creep strength and retention of ductility (“stability”) after creep exposure. “Stability” is assured if Ti-6Al-2Sn-2Zr is found to be the creep/density optimized stable alloy. The alloying behavior of Ti is consistent with a “metallic bonding valence” of four and an “alloy structure valence” of 1.5. Covalent bonding between Ti and Al is confirmed. This substantially precludes blocking Al embrittlement through dilution of alpha soluble additions of elements from groups IV B , V B and VI B . Ti-6Al-2Sn-4Zr-2Mo is shown to have good hot strength and creep resistance. Between about 850° and 1050°F, Ti-6Al-2Sn-4Zr-2Mo obeys a creep rate equation of the general form for small strains and strain rates.

Effect of Alloy Composition on Stress Corrosion Cracking of Fe-Cr-Ni Base Alloys

Abstract: This study investigated the effect of alloying on the behavior of Fe-Cr-Ni base alloys in boiling MgCl2 solutions. Alloys included commercial Fe-Cr-Ni alloys; ternary Fe-Cr-Ni alloys to 40% Cr; fourth-component alloys with specific alloy bases; fourth-, fifth-, and sixth-component alloys. The primary experimental measurements were time-to-breaking of wire specimens. In addition, polarization, potential time, current decay, constant potential cracking, and metallographic studies were conducted. Alloys of very substantial improvement in resistance to cracking were found. The most effective alloy additions were found to be aluminum, beryllium, and carbon. Lowering chromium to the 10-15% range was also found to be very effective in preventing cracking. The results are discussed in terms of the slip-step dissolution model of stress corrosion cracking.

Thermoelectric power and thermal conductivity in the silver-gold alloy system from 3-300°K

Abstract: The thermal conductivity, thermoelectric power and electrical resistivity for a series of 20 annealed polycrystalline Ag—Au alloys, covering the whole 100% α-solid solution range of the system, have been measured from 3° to 300°k. The thermoelectric power has been separated into diffusion and phonon drag components and the effect of Fe impurities has been taken into account. The attenuation of the phonon drag peak on alloying cannot be explained simply by the corresponding attenuation of the lattice component of the thermal conductivity, nor does it show the resurgence at high solute concentrations previously observed in other noble metal alloy systems.

Sulfide shape control in high strength low alloy steels

Abstract: Directionality of mechanical properties—such as toughness and bend formability—is typical of hot rolled steels processed on modern, hot strip mills. In aluminum killed steels, directionality results mainly from elongated (type II) manganese sulfide inclusions. Directionality can be reduced by retaining the original globular shape of the precipitated sulfides. This can be accomplished by promoting the formation of sulfides which are more stable and have a higher melting point than that of manganese sulfide. Thermodynamic considerations indicate that additions of Ti, Zr, Ca, Mg, and rare earths are suitable for this purpose. Experimental work on laboratory heats containing 0.020 to 0.25 pct S involved mainly additions of rare earths (mischmetal or silicides) to a V−Al−N high strength, low alloy steel. Other strong sulfide formers were not utilized either because of too high vapor pressure at steelmaking temperatures or because of their strong interaction with nitrogen. For cerium contents of 0.03 to 0.04 pct, the shape of inclusions, identified as rare earth sulfides, was globular. Control of sulfide shape contributed to a marked improvement in toughness and formability of steel in the direction transverse to the rolling direction. The results have been verified in full scale plant trials.

Solid solution strengthening in Nb-Ta and Nb-Mo alloy single crystals

Abstract: The strength of Nb, Nb-Ta, and Nb-Mo alloys was investigated in tension and compression as a function of composition, temperature, and strain rate. The room-temperature properties show molybdenum to have a significant effect on the strength of niobium while the effects of tantalum are nearly zero. The room-temperature strength is shown to be well correlated with the atomic misfit parameter. Analysis of the low-temperature behavior of Nb-Ta alloys indicates that they behave similarly to the pure metal while Nb-Mo alloys show a marked deviation from this behavior. The strengthening phenomena occurring in the Nb-Mo alloys at low temperature is interpreted as being an impurity interaction. A transition between the mechanism operating in the pure metal and the impurity interaction occurs at low solute contents.

Composites of glass-ceramic-to-metal,seals and method of making same

Abstract: GLASS OR CERAMIC-TO-METAL COMPOSITIES OR SEALS WHEREIN THE GLASS OR CERAMIC IS BONDED TO A COPPER BASE ALLOY HAVING A THIN FILM OF AL2O3 ON ITS SURFACE. THE AL2O3 FILM COMPRISES AT LEAST 10%, UP TO 100%, OF THE OXIDE FILM THICKNESS ON THE METAL. THE COPER BASE ALLOY PREFERABLY CONTAINS 2 TO 10% ALUMINUM WITH C.D.A. ALLOY 638 BEING THE MOST PREFERRED ALLOY. THE INVENTION ALSO INCLUDES THE PROCESS OF BONDING THE GLASSES OR CERAMICS TO THE METAL. SUBSTANTIAL MISMATCH BETWEEN THE COEFICIENT OF THE THERMAL EXPANSION OF THE GLASSES OR CERAMICS AND THE COPPER BASE ALLOYS MAY BE TOLERATED IN ACCORDANCE WITH THIS INVENTION.

Method of fabrication of semiconductor device package

Abstract: Method of electrically interconnecting two electrical components, e.g. a semiconductor chip and a substrate, via contacts formed of aluminum, gold or silver by joining the contacts with a body of metal containing germanium and the same metal from which the contacts are formed, and heating the body of metal to the melting temperature of the eutectic alloy formed between germanium and the alloy.

The Production of Plane Surfaces on Single Crystals of Copper and Copper Alloys

Abstract: Chemical and electrochemical polishing methods which allow submicroscopically smooth optically flat surfaces to be produced on crystals of copper and copper alloys are described. This is made possible by the use of solutions for cloth chemical polishing which have as additives nitrogen‐containing mercapto‐sulfur compounds and surface active agents, which facilitate rapid flattening of the surfaces. Conditions for producing surfaces with the best compromise between flatness and submicroscopic smoothness have been worked out. A new system in which an endless cotton belt, saturated with a phosphoric acid electrolyte containing chromic acid, moves between a stationary cathode and the stationary anodic specimen has been introduced for electrochemical finishing. This almost eliminates the fine grained structure often seen on electropolished surfaces of alloy crystals.

Treatment of alloys

Abstract: A method of making a heat-recoverable article in which an alloy comprising an intermetallic compound, which on cooling transforms into a banded martensite by shear with or without working, deformed after appropriate heat treatment so that on reheating it at least partly resumes its original shape. It is preferred to use a copperbase alloy which transforms into a martensite of pseudocubic symmetry.