Showing papers on "Alloy published in 1971"
TL;DR: In this article, the elastic and plastic properties of filaments of non-crystalline Pd 20 a/o Si alloy and the changes that occur on crystallization during and after heating at various temperatures have been examined.
435 citations
TL;DR: In this paper, it was shown that lithium metal can alloy with other metals including noble metals in an organic electrolyte electrochemical cell: in propylene carbonate/metal at ambient temperature with the evolution of electrical energy.
Abstract: Lithium metal was found to alloy with the other metals including noble metals in an organic electrolyte electrochemical cell: in propylene carbonate/metal at ambient temperature with the evolution of electrical energy. The alloying occurred in many organic electrolytes containing lithium ions. Both the coulombic efficiency and the rate of alloying were found to be high. The alloys were gray to dark gray and brittle. Chemical and x‐ray analysis indicated that they were intermetallic compounds.
352 citations
TL;DR: The magnetic phase diagram of γ Fe-Mn alloys has been investigated in the whole range of composition by neutron diffraction and other techniques as discussed by the authors, and the results agree qualitatively with the prediction based on the band theory.
Abstract: The magnetic phase diagram of γ Fe-Mn alloys has been investigated in the whole range of composition by neutron diffraction and other techniques. The f.c.c. phase of Fe-Mn alloys with less than 40 at. % iron and more than 85 at. % iron was stabilized by addition of small amounts of copper and carbon respectively in the alloys. An antiferromagnetic long range order was detected in the whole range composition. The antiferromagnetism of this alloy system Fe x -Mn 1- x was found to be classified into three distinct groups according to the composition. They are 1) 0≤ x ≤0.3, 2) 0.4≤ x ≤0.8, and 3) 0.8≤ x ≤1. The magnetic phase of the second group is markedly different from other two groups. The results agree qualitatively with the prediction based on the band theory.
323 citations
TL;DR: In this article, the effect of catalytic effect of Cu and P on the oxidation of Fe(II) hydroxo-complexes in aqueous solutions has been investigated and the mechanism of atmospheric rusting deduced from the results obtained in the present investigation has been used to explain the difference in behaviour between ordinary mild steels and low alloy steels during atmospheric exposure.
236 citations
TL;DR: In this paper, structural ageing characteristics of aluminium alloys containing 2 and 4 wt.-% lithium are reported and thin-film electron microscopy was used to confirm the ordered L12-typestructure of the δ′ and to study the precipitate size and distribution over a range of ageing temperatures.
Abstract: The structural ageing characteristics of aluminium alloys containing 2 and 4 wt.-% lithium are reported. One transition phase (AI3Li, δ′) occurs in the alloy system and time-temperature-transformation curves have been determined for this phase and the equilibrium precipitate. Strengthening in these alloys is associated with δ′ precipitation, the peak hardness increment occurring in the 2% alloy after ageing for 24 h at 200°C (473K). Thin-film electron microscopy was used to confirm the ordered L12-typestructure of the δ′ and to study the precipitate size and distribution over a range of ageing temperatures. At low temperatures the δ′, which has a spherical morphology, is very fine (∼ 0.01 μm at 100°C, 373K) and resists coarsening. Above 200°C (473 K) coarsening is rapid and the process has been analysed using the Lifshits-Wagner theory. The δ′ interfacial energy was estimated to be ∼ 240 erg/cm2 (0.24 J/m2) and the lattice mismatch 0.18%. At and below 60°C (333K), ageing is accompanied by an incre...
222 citations
TL;DR: In this paper, the shape-memory effect has been studied in a titanium −35 wt.-% niobium alloy and the effect is observed under two different sets of conditions: when the fully martensitic alloy is deformed below Ms, it recovers its original shape when heated above As and if the alloy is artificially depressed by a fine dispersion of ω-phase precipitates, which prevents the martensite forming on cooling through the expected Ms, a strain-induced martensites is formed and on heating above As the deformation is recovered.
Abstract: The shape-memory effect has been studied in a titanium −35 wt.-% niobium alloy. The effect is observed under two different sets of conditions. First, when the fully martensitic alloy is deformed below Ms it recovers its original shape when heated above As Secondly, if the alloy is deformed between Ms and As (with Ms artificially depressed by a fine dispersion of ω-phase precipitates, which prevents the martensite forming on cooling through the expected Ms , a strain-induced martensite is formed and on heating above As the deformation is recovered. When the orthorhombic martensite forms from the cubic β phase, there is an expansion of the unit cell along two axes of the orthorhombic and a contraction along the third. The orientation relationship between the two phases predicts 12 possible variants and on stressing that variant will be formed which results in a relief of the stress, e.g. under a tensile stress those lattice planes with an increased spacing in the orthorhombic phase will tend to lie ...
166 citations
01 Mar 1971
TL;DR: An electrochemical method has been used to determine the permeability,P, diffusion coefficient,D, and solubility,c, of hydrogen in alloys of the Fe-Ni system as discussed by the authors.
Abstract: An electrochemical method has been used to determine the permeability,P, diffusion coefficient,D, and solubility,c, of hydrogen in alloys of the Fe-Ni system The heats of activation for diffusion and the heats of solution have been derivedD falls from ≃10−4 sq cm per sec for pure iron to ≃10−10 sq cm per sec for 40 wt pct of Ni in the alloy Thereafter it rises slightly to that for pure nickel,c rises by about 103 between pure iron and 40 wt pct Ni, then remains constant up to pure nickel The resultantP doubles at 5 wt pct Ni and then falls by 103 times up to 40 wt pct Ni, afterwards rising slightly to that for pure nickel Between 0 and 40 wt pct Ni the dominant factor in controlling the value ofP is the fall of the mole fraction of the α phase in the alloy This hypothesis gives a reasonable quantitative calculation of theP-composition relation Between 40 and 100 wt pct, the crystallographic phase is allγ and the major effect is the bonding of hydrogen in the alloy, the small changes noted being reasonably calculable The negligible change of solubility in this region reflects the negligible change ind character of the alloy from 40 to 100 wt pct Ni The hydrogen permeability of Fe-Ni (5 wt pct) is greater than that of palladium atT > 200°C The corrosion rate and hydrogen permeability (hence, susceptibility to hydrogen embrittlement) pass through a minimum at about 50 wt pct Ni A remarkable parallelism exists between corrosion rate and hydrogen permeation in Fe-Ni alloys An interpretation is suggested
162 citations
TL;DR: In this paper, the densities of states of the near ideally substitutional random-alloy system Cu-Ni are calculated using the coherent-potential approximation for a range of concentrations of the constituents across the complete alloy diagram.
Abstract: The densities of states of the near ideally substitutional random-alloy system Cu-Ni are calculated using the coherent-potential approximation for a range of concentrations of the constituents across the complete alloy diagram. It is shown that previous model calculations for Ni-rich paramagnetic Cu-Ni alloys using the coherent-potential approximation can be extended to alloys of arbitrary concentration if appropriate Cu and Ni potential functions are used. The results obtained are consistent with experimental photoemission and soft-x-ray emission profiles in so far as comparisons can be effected. The results indicate the limits of this simple nonmagnetic random-alloy theory for discussing the conventional low-temperature specific-heat data of these alloys. For Cu-rich alloys the results correspond to a split-band regime while for Ni-rich alloys the $d$ bands associated with Cu and with Ni sites in the alloy overlap to a considerable extent. For all Cu-Ni alloys the rigid-band model and the virtual-crystal approximation are quite inappropriate.
157 citations
01 Jan 1971
TL;DR: In this paper, the effect of ternary additions of Al, O, Sn, and Zr on the decomposition of metastable Ti-Mo and Ti-V Β-phase alloys has been studied.
Abstract: The effect of ternary additions of Al, O, Sn, and Zr on the decomposition of metastable Ti-Mo and Ti-V Β-phase alloys has been studied. It is shown that all these additions reduce the volume fraction, upper temperature limit of formation, and time of stability of the Ω phase. These results have been contrasted to earlier work in binary alloys in which misfit was shown to be a primary factor in determining the morphology and range of stability of the Ω phase. In the ternary alloys the particle morphology can still be explained in terms of misfit, but other considerations appear to be predominant in determining the range of stability. Results are also presented on a phase separation reaction which occurs at higher alloy contents and which has an important influence on the morphology of α-phase precipitation.
155 citations
TL;DR: In this paper, the authors made thermodynamic calculations of the equilibria in and near grain boundaries in order to determine the chromium content in the vicinity of carbide particles.
Abstract: The well‐known susceptibility of austenitic stainless steels to intergranular corrosion after heat‐treatment in the temperature range of 550°–800°C (i.e., "sensitization") has long been attributed to depletion of Cr from regions of the alloy matrix adjacent to grain boundaries in which had precipitated. Those regions of the steel in which the local Cr composition falls below about 12% have a diminished ability to form a passive film and hence corrode preferentially.We have made thermodynamic calculations of the equilibria in and near grain boundaries in order to determine the chromium content in the vicinity of carbide particles. The calculations show that the equilibrium chromium content is a strong function of the temperature and of the carbon and alloy content of the steel. It is inferred from the analysis that variations in the susceptibility to intergranular attack are determined primarily by changes in the equilibrium chromium content near the carbides and not by changes in the number and distribution of particles. For instance, above 800°C the chromium content near the carbides is high enough to produce passivity, and the alloy is immune not because of the absence of carbides but because chromium depletion is not severe. Experimental studies of rates of grain boundary attack as functions of temperature and composition have confirmed the predictions of the analysis.A further factor of less importance is the distribution of carbides in the grain boundary. Calculations were made to determine the Cr concentration gradient within the boundary between carbide particles as a function of temperature and composition as well as the Cr gradient normal to the boundary. These calculations predict a strong interdependence between susceptibility to intergranular corrosion, carbide particle spacing, and sensitizing temperature. Experimental results on thinned samples of sensitized material corroded in a Strauss solution and examined by electron microscopy are in good agreement with predicted effects.
155 citations
TL;DR: In this article, a model is proposed for the interphase precipitation which takes into account the observed morphology and crystallography of the carbide phases and of the ferrite in an iron +6.3wt% tungsten +0.23wt% carbon alloy in which M$6}$C precipitates on a much coarser scale.
Abstract: Austenite containing 1 to 2 wt% vanadium and 0.2 wt% carbon, held in the range 600 to 850 degrees C transforms to an extremely fine dispersion of V$\_{4}$C$\_{3}$ in ferrite. The carbide particles are nucleated on the $\gamma $-$\alpha $ phase boundary at successive positions during the transformation, forming sheets of precipitate which are 5 to 30 nm apart, while the individual particles are 3 to 10 nm diameter (interphase precipitation). High resolution electron microscopy has provided details of the morphology and crystallography of the carbide particles and the transformation front. A similar reaction has been studied in an iron +6.3wt% tungsten +0.23wt% carbon alloy in which M$_{6}$C precipitates on a much coarser scale enabling precise observations to be made on the transformation front. Interphase precipitation has also been examined in an iron +3.45 wt% molybdenum +0.22 wt% carbon alloy. A model is proposed for the interphase precipitation which takes into account the observed morphology and crystallography of the carbide phases and of the ferrite.
Patent•
01 Jul 1971TL;DR: In this article, the authors describe the preparation of cubic boron nitride (CBN) CRYSTALS on a SINTERED CARBIDE MASS.
Abstract: ALUMINUM ALLOYS OF NICKEL, COBALT, MANGANESE, IRON, VANADIUM AND CHROMIUM HAVE BEEN FOUND TO PROVIDE SUCCESSFUL BONDING MECHANISMS FOR THE PREPARATION OF CUBIC BORON NITRIDE (CBN) COMPACTS. THESE BONDING MEDIA ARE PARTICULARLY EFFECTIVE FOR PREPARING COMPACTS OF CBN CRYSTALS SMALLER THAN ABOUT 30 MICROMETERS IN LARGEST DIMENSION. THE PREPARATION OF TOOL INSERTS MADE OF CUBICBORON NITRIDE CRYSTALS BONDED TO AND SUPPORTED ON A SINTERED CARBIDE MASS IS DESCRIBED WHEREIN SUCH AN ALUMINUM ALLOY IS USED AS THE BONDING MEDIUM.
TL;DR: The structure and nature of ledges at three faceted precipitates, θ 1 and θ 2 in an aluminum-4 wt. % copper alloy, and β(Mg 2 Si) in an aluminium-1.5 Wt.% Mg 2Si alloy, have been determined by electron microscopy.
TL;DR: In this article, the open circuit voltages of a cell were measured over a composition range of 6.9-50 a/o (atom per cent) alloy in the temperature range 282°-389°C.
Abstract: The open‐circuit voltages of the cell were measured over the composition range of 6.9–50 a/o (atom per cent) alloy in the temperature range 282°–389°C. The composition of the alloy was varied by coulometrically charging and discharging the cell. The emf values of the cell are independent of the composition up to 47 a/o lithium in the alloy and their temperature dependence follows the relationship , where is in millivolts, , and σ is the standard deviation. The constant potential exhibited by the alloy is ascribed to the formation of phase on the alloy surface. The standard free energies of formation for are estimated to be −7.49, −7.24, and − 7.09 kcal/mole at 300°, 350°, and 380°C, respectively. The standard enthalpy and entropy of formation are constant, −10.40 kcal/mole and −5.08 cal/mole deg, respectively, in this temperature range. Since the electrochemically prepared lithium‐aluminum alloy has a constant potential over a wide composition range and exhibits good electrochemical behavior, it can serve as a good reference electrode as well as a high energy density anode in molten salt systems containing lithium.
DOI•
01 Jul 1971TL;DR: The effect of the precipitation of the metastable ω phase on the tensile properties of β-phase titanium alloys has been studied in this article, where the volume fraction of ω was varied by controlling the heat treatment temperature and the alloy content.
Abstract: The effect of the precipitation of the metastable ω phase on the tensile properties of β-phase titanium alloys has been studied. The volume fraction of ω phase was varied by controlling the heat treatment temperature and the alloy content. It is shown that provided the volume of ω phase is less than 0.6, significant increases in yield strength can be obtained while retaining reasonable ductility. Higher volume fractions results in complete macroscopic embrittlement, but fracture still occurs by microvoid coalescence. Thin film microscopy of deformed samples shows that dislocations bypass the omega particles. The results are discussed in relation to current theories of deformation and fracture of two-phase alloys.
01 Aug 1971-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the fracture toughness of a high carbon TRIP alloy, deformed approximately 75 pct at 460°C was investigated over a range of temperatures from −196°C to 200°C.
Abstract: The fracture toughness of a high carbon TRIP alloy, deformed approximately 75 pct at 460°C was investigated over a range of temperatures from −196°C to 200°C. Two distinct temperature regimes were present: a low temperature regime where martensite formed during fracturing and a high temperature regime where no martensite formed. The toughness values of the low temperature regime were higher than the extrapolated values of the high temperature regime indicating that the transformation makes a positive contribution to the fracture toughness of TRIP alloys. For the alloys used in this investigation the room temperature plane strain fracture toughnessK IC was on the order of 95 ksi\(\sqrt {in} \) or in terms of the crack extension forceG IC, 274 in.-lb per sq in. The fracture mode was cleavage and the extraordinary toughness for this mode of crack extension is attributed to the energy absorbed by the simultaneous phase transformation. The contribution due to the phase transformation was determined to be in the range 37 to 57\(\sqrt {in} \) in terms of stress intensity or 168 to 232 in.-lb. per sq in. in terms of crack extension force using the extrapolation technique. The results obtained using the extrapolation technique represent the first experimental determination of the toughness contribution associated with the austenite to martensite phase transformation in TRIP alloys. An expression for the toughness associated with the transformation was derived using fundamental fracture mechanics relations. This expression, which contains easily measured parameters, was used to calculate the toughness contribution due to the phase transformation and the results were in good agreement with the experimental values.
01 Oct 1971
TL;DR: In this paper, a new mechanism for the inhibition reaction between iron and zinc is proposed, where a thin layer of an Fe-AlZn ternary compound forms on the iron surface and inhibits the growth of Fe-Zn phases.
Abstract: The reaction mechanisms and the structures of the phases formed during the hot dipping of iron in 0 to 10 pct Al-Zn alloy baths at temperatures of 450° to 700°C were studied by X-ray diffraction and electron microprobe analysis techniques. A new mechanism for the inhibition reaction between iron and zinc is proposed. At bath temperatures below 600°C, a thin layer of an Fe-Al-Zn ternary compound forms on the iron surface and inhibits the growth of Fe-Zn phases. Breakdown of inhibition occurs during the dipping process when the ternary compound becomes rich in aluminum and transforms to a more stable structure which is isomorphous with Fe2Al5. While this breakdown is occurring, the zinc atoms react with iron and form the conventional Fe-Zn phases.
TL;DR: The temperature dependence of the internal friction and Young's modulus of the glassy and crystalline phases of a Pd 0.76 Au 0.75 Si 0.165 alloy have been determined by a resonance technique.
Abstract: The temperature dependence of the internal friction and Young's modulus of the glassy and crystalline phases of a Pd 0.76 Au 0.75 Si 0.165 alloy have been determined by a resonance technique. The internal friction of the glassy alloy increases exponentially above 150°C at a frequency of 140 Hz. The apparent activation energy of the relaxation process increases upon annealing from 50 to 80 kcal/mole. It is suggested that relaxation processes possessing a broad spectrum of activation energies are active in the glassy alloy. Young's modulus of the glassy alloy decreases gradually with increasing temperature and increases approximately 28% upon crystallization.
TL;DR: Stages in the development of a protective α-Al2O3 scale on a Ni-15Cr-6Al (wt.%) alloy have been examined in this paper, where it is shown that prior to the formation of a continuous α-al 2O3 layer, a transient stage of oxidation occurs that consists of a rapid uptake of oxygen with conversion of a thin surface layer of alloy to predominantly spinel and the subsequent development of discrete layer of Cr2O 3.
Abstract: Stages in the development of a protective α-Al2O3 scale on a Ni-15Cr-6Al (wt.%) alloy have been examined. It is shown that prior to the formation of a continuous α-Al2O3 layer, a transient stage of oxidation occurs that consists of a rapid uptake of oxygen with conversion of a thin surface layer of alloy to predominantly spinel and the subsequent development of a discrete layer of Cr2O3. It is also shown that during the transient period of oxidation metastable phases of aluminum oxide are formed which transform to α-Al2O3 upon incorporation into the external oxide scale.
TL;DR: In this paper, two Cu-Ni-Fe alloys of asymmetrical compositions (i.e., with unequal volume fractions of the two low temperature phases) were heat treated to produce spinodal structures with various wavelengths or characteristic particle spacings.
01 Sep 1971
TL;DR: In this paper, the grain structure of catalytically clean Ni−Cu alloys is examined as a function of the degree of supercooling below the equilibrium liquidus, and it is concluded that solute elements can promote grain formation in certain castings at supercoolings insufficient to cause heterogeneous nucleation.
Abstract: Two related experimental programs on the solidification structure of alloy castings are reported. In the first, the grain structure of catalytically clean Ni−Cu alloys is examined as a function of the degree of supercooling below the equilibrium liquidus. For supercoolings greater than 85°C, the Ni−Cu alloys exhibit a structure which is in accord with previous observations in pure nickel,i. e., the structure is found to be coarse and dendritic in the range 85° to 150°C supercooling, but fine and equiaxed for supercoolings greater than 150°C. However, in the lower range of supercooling (<85°C) the structure is fine and equiaxed. It is concluded that solute elements can promote grain formation in certain castings at supercoolings insufficient to cause heterogeneous nucleation. To study the effect of solute elements on the structure of a solidifying material, castings of pure nickel and aluminum are compared with binary alloys of these base materials. Over the composition ranges studied in both alloy systems, the structure is observed to be related to a parameter which includes the slope of the liquidus, the bulk solute concentration, and the solute distribution coefficient. It is shown or is argued that heterogeneous nucleants are not involved and therefore another mechanism must be operating in determining the structure. In any event, these latter experiments suggest that an effective means of controlling the structure of castings is by appropriate selection of alloying additions on the basis of the alloy variables contained in such a parameter.
01 Nov 1971-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, the influence of microstructure on the strength and fracture toughness of 18 Ni maraging steel was examined by X-ray and neutron diffraction and by optical and electron microscopy.
Abstract: The influence of microstructure on the strength and fracture toughness of 18 Ni (350) maraging steel was examined. Changes in microstructure were followed by X-ray and neutron diffraction and by optical and electron microscopy. These observations have been correlated with the fracture morphology established by scanning electron microscopy. Air cooling this alloy from the austenitizing temperature results in a dislocated martensite. During the initial stage of age hardening, molybdenum atoms tend to cluster (forming preprecipitates) and the cobalt assumes short range ordered positions. Subsequent aging results in Ni3Mo and σ-FeTi with overaging being associated with the formation of equilibrium reverted austenite and Fe2Mo. The fracture behavior is examined in terms of elementary dislocation precipitate interactions. It is suggested that the development of coplanar slip in the underaged conditions leads to its increased stress corrosion susceptibility and decreased fracture toughness. The optimum aged condition is then associated with cross-slip deformation. The fracture behavior of the overaged condition is a dynamic balance between a brittle matrix and the ductile (crack blunting) reverted austenite.
TL;DR: In this paper, a detailed structural examination of the alloy Nb44 % Ti has been carried out to gain a better understanding of flux pinning in a typical commercial type II superconductor.
TL;DR: The nucleation of martensite is studied in defect-free single crystals of iron and iron-nickel over a size range of 0.002-0.2 µm as discussed by the authors.
01 Jan 1971
TL;DR: Fracture toughness of an α-Β titanium alloy heat treated to a constant yield strength has been found to depend upon the morphology of α produced or remaining after the initial solution treatment.
Abstract: Fracture toughness of anα-Β titanium alloy heat treated to a constant yield strength has been found to depend upon the morphology of α produced or remaining after the initial solution treatment. In equiaxed α structures, fracture toughness depends linearly upon the grain boundary area per unit volume,Sv, and is independent of equiaxed α particle size or spacing. In a grain boundary α structure fracture toughness depends both onSv and, within limits, linearly on the thickness of the α. Explanations are offered for the observed propagation of cracks at α-@#@ Β interfaces and for the observation that high fracture toughness can accompany low tensile ductility.
TL;DR: In this article, the growth kinetics of passive films on Fe, Fe, 10, Ni, Fe-10 Cr, Fe 10 Cr, Ni 10 Cr and Fe 10 Ni 1 Cr were determined in pH 8·4 borate buffer solution at 25°C using ellipsometer and coulometric techniques.
TL;DR: In this paper, low temperature and composition effects on alloy softening in group 6A metals alloyed with reagents were studied and shown to have a significant effect on softening.
Abstract: Low temperature and composition effects on alloy softening in group 6A metals alloyed with Re
Patent•
04 Oct 1971
TL;DR: The flame spraying of high temperature plastic powder as for example polyimides, polyamide-polyimides or polyester imides, or aromatic polyester high temperature plastics in admixture with a flame spray metal powder such as aluminum alloy, nickel, copper, bronze, babbitt or stainless steel flame spray powder as discussed by the authors.
Abstract: The flame spraying of high temperature plastic powder as for example polyimides, polyamide-polyimides, polyester imides, or aromatic polyester high temperature plastics in admixture with a flame spray metal powder as for example aluminum alloy, nickel, copper, bronze, babbitt or stainless steel flame spray powder.
TL;DR: Aromatic hydrocarbon films display field-induced switching between two impedance states when a mobile electrode material such as gallium-indium alloy is employed as mentioned in this paper, and the switching mechanism involves the formation of conducting filaments.
Abstract: Field-induced switching between two impedance states has been observed in both pure and doped organic thin films. Aromatic hydrocarbon films display this phenomenon reproducibly when a mobile electrode material such as gallium-indium alloy is employed. Controlled doping of the hydrocarbons with electron acceptors leads to reproducible switching characteristics which are not electrode dependent. For the doped films, activation energies of conduction typical of bulk charge-transfer complexes characterize the low impedance states whereas the activation energies of the high impedance states are typical of organic insulating films. It is suggested that the switching mechanism involves the formation of conducting filaments.