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Quantitative metallography is often used to confirm the proper processing of aerospace metallic materials. A microstructural feature of great importance for titanium alloys processed in the alpha-beta phase field is the volume fraction of primary alpha. S...

British Library Electronic Table of Contents (United Kingdom)

A microanalytical characterization of cast magnesium alloys of eutectic origin based on the Mg?Al?Ca ternary matrix system has been carried out in order to investigate the influence of alloying elements on their microstructure as well as microchemistry-processing-microstructural relations using structure-sensitive techniques of electron microscopy, mechanical spectroscopy (internal friction), X-ray diffractometry, and advanced microanalytical methods including electron probe compositional analysis. Following the data obtained here there is direct correlation of microstructure with creep properties of the new experimental magnesium alloys. The creep and heat-induced properties of the multicomponent magnesium alloys containing low range of inexpensive additions of titanium (0.07?0.2%) or str...

International Nuclear Information System (INIS)

Zirconium-base alloys are used primarily as fuel cladding material and other core structure material in water cooled nuclear power reactors. Main research achievements and problems about corrosion of zirconium alloys are reviewed; the present theories and challenge are summarized. In the 1980s, great progress had been made towards correlating alloy composition, microstructure and irradiation with corrosion resistance. In the 1990s, main researches are focused on exploring actual mechanism of corrosion, optimizing both alloy composition and microstructure in order to minimize the fuel cycle costs through burnup optimization.

International Nuclear Information System (INIS)

The relationships of hydrogen alloyed #beta#-titanium alloy deformation behaviour to its microstructure and texture are investigated. It is shown that plasticity increases and strain induced texture changes at low hydrogen contents (0.1-0.2 mass %). Possible mechanisms responsible for specific features of #beta#-Ti alloy deformation are discussed. The study is made using alloy VT35 doped with hydrogen

International Nuclear Information System (INIS)

(Feb 1972). United States Nelson, HG Williams, DP Stein, JE v. 3(2)

International Nuclear Information System (INIS)

In order to substitute expensive cast titanium alloys by powder ones the possibility of introduction of powder additions by mechanical stock mixing is studied. It is shown that microstructure of powder alloys of Ti-Zr(1-9%) system is typical for one-phase cast #alpha#-alloys. The Ti-Mo(1-9%) and Ti-Nb(1-9%) system alloys have microstructure typical for two-phase (#alpha#+#beta#)-alloys. For homogeneous structure to be obtained the high temprature annealing is advisable after hot pressing. Alloying with Mo, Zr and Nb permits to increase considerable the strength of powder titanium products (at 9% Mo more than two times).

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In this study, deformation modes and precipitations have been characterized in test pieces made of alloy 800, grade 2 hyper-hardened state and age-conditioned for 3000 h at 550/sup 0/C, used for steam generator tubes of the Super Phenix Reactor, after continuous fatigue and fatigue-relaxation tests in the oligocyclic range. This microstructural study has provided an interpretation of the fatigue behaviour of the material.

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In the present work, electrochemical measurements and corrosion tests in NaCl solutions were carried out to study the effect of aging treatments on pitting corrosion behavior in a 8090 alloy and its high purity Al-Li binary alloy analogue. The pitting corrosion characteristics and corrosion resistance of the 8090 alloy have been determined in relation to precipitation microstructures. (orig.).

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Recent developments on plastic forming technology of magnesium alloys are presented. Attempts have been undergoing with an aim at forming magnesium alloy parts at lower temperatures. It is believed that fine microstructure magnesium alloys usually have much higher plasticity at lower temperatures and even room temperatures. Extrusion is a method to form magnesium profile products and tube products, which is also one of the effective ways to make fine microstructure magnesium alloys. Superplasticity forming is another method to form high plasticity magnesium alloys. Hot forming of magnesium sheet parts is an important process to form magnesium products. Some developments related to above issues are discussed in the present paper. (orig.)

International Nuclear Information System (INIS)

In the heat-affected zones (HAZ) of low alloy steels used for nuclear pressure vessel, microstructural changes, such as grain coarsening, carbide precipitation, and martensite formation, generally occur and cause a deterioration of toughness and an increase in sensitivity to brittle fracture. Metallographic analyses of low alloy steel welds reveal significantly different regions in HAZ microstructures. In 2-pass welds, there were seven characteristic regions in the HAZ determined by the peak temperature, to which the region was exposed during the weld thermal cycle: a coarse-grained region, a fine-grained region, an intercritical region, and subcritical region. The coarse-grained region can be categorized into four zones according to the reheating temperature as follows : an unaltered coarse-grained zone (UCGHAZ), a supercritically reheated coarse grained zone (SCRCGHAZ), an intercritically reheated ...

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Mg-3%Al-1%Zn (AZ31) alloy was subjected to ECAE processing at 523 and 573 K. Microstructure observation and texture analysis were carried out using optical microscope and SEM-EBSD technique in order to investigate the process of microstructural changes including texture development during ECAE processing. Grain refinement during ECAE processing is enhanced by dynamic continuous recrystallization. The texture of the ECAE-processed AZ31 alloy specimens change with ECAE processing temperature, and the textural changes relate to deformation mechanisms that change with ECAE processing temperature. (orig.)

International Nuclear Information System (INIS)

SP-700, an emerging #beta#-rich #alpha#+#beta# titanium alloy, is designed to improve superplastic formability as well as mechanical properties over Ti-6Al-4V alloy. Owing to its fine microstructure and low #beta#-transus temperature, it is superplastic-formable at temperature below 1,073K (800 C) with low flow stress. Remarkable workability of this alloy is also retained in conventional Manufacturing processes. Another advantage of SP-700 is heat treatment response which includes deep hardenability and quick aging kinetics. Corrosion resistance and machinability are equivalent to or better than Ti-6Al-4V alloy.

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Mechanical alloying is an important pre-requisite for the manufacturing of heat resistant oxide-dispersion-strengthened superalloys. Though the microstructure of these materials after hot extrusion and recrystallization treatment is well documented, little is known about the microstructural evolution during ball-milling. A method was tested to prepare electron transparent foils and extraction replica from powder particles for TEM investigations. The microstructure was found to consist of a Ni-Cr-Al solid solution in which submicron particles of refractory metals were embedded. The extremely fine grainize of about 50 nm is the consequence of severe plastic deformation. Yttria particles could not be detected in the powder after ball milling, but after a heat treatment at 1000 C the well-known fine dispersion of oxide particles was evident. (orig.)

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With the ever increasing awareness of the toxicity of Pb, significant pressure has been put on the electronics industry to get the Pb out of solder. This work pertains to the development and characterization of an alloy which is Pb-free, yet retains the proven positive qualities of current Sn-Pb solders while enhancing the shortcomings of Sn-Pb solder. The solder studied is the Sn-4.7Ag-1.7Cu wt% alloy. By utilizing a variety of experimental techniques the alloy was characterized. The alloy has a melting temperature of 217{degrees}C and exhibits eutectic melting behavior. The solder was examined by subjecting to different annealing schedules and examining the microstructural stability. The effect of cooling rate on the microstructure of the solder was also examined. Overall, this solder alloy shows great promise as a viable alternative to ...

International Nuclear Information System (INIS)

The optimum of strontium amount for good modification of AK7, AK9, AK11, AK52, AK104 alloys was determined on the base of the analysis of microstructural changes. The stability of the modifier was investigated on the way of successive remelting of billets. The influence of amount of modifier on the impact strength of the alloys was established. (author)

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AZ31 magnesium alloy was friction-welded to AM60 and the microstructures and the friction welding process were studied. The microstructures changed near the weld interface. The AZ31 was refined to a grain size of several {mu}m near the weld interface. The nucleation occurred in the shear bands that were introduced during the welding process. On the other hand, the eutectic structure was deformed and the lamellar structure which was composed of {alpha}-Mg and Mg{sub 17}Al{sub 12} was formed near the weld interface in AM60 alloy. In the friction process, the adhesion and peel off occurred alternately between AZ31 and AM60. Eventually, bonding was completed during upset process. (orig.)

International Nuclear Information System (INIS)

Results of investigation on the effect of microstructure and deformation conditions (temperature and strain rate) on flow stress and critical strain in two phase #alpha# + #beta# titanium alloy Ti-6Al-5Mo-5V-1Cr-1Fe is presented in the paper. The alloy is deformed or torsional plastometer at temperature range 1073-1173 K and at the strain rate #epsilon# = 0.04-4.0 s"-"1. Sequential deformation at 1173 K at the strain rate of 0.4 s"-"1 was also performed with holding times in the range 1-100 s. The fraction of dynamically and metadynamically recrystallized #beta# phase was determined on the basis of results of sequential deformation test. Microstructure was examined using LM and TEM techniques. (author)

British Library Electronic Table of Contents (United Kingdom)

The microstructure and tensile properties of Ti-44Al-6V-3Nb-0.3Y (at.%) alloy after canned forging were investigated. SEM results showed that the TiAl pancake exhibits inhomogeneous microstructure, which can be ascribed to the temperature drop and friction between billet and outer pack during forging, as well as the intrinsic anisotropy of lamellar colony. By means of TEM observation and EBSD analysis, the microstructure in the dominant area of the pancake was further characterized. This deformation area consists of 87.7% content of g grains plus some refined lamellar colonies and the rest of B2 grains. The grain size ranges between 1mm and 8.5mm. High-angle boundaries dominate the deformation microstructure, several substructures and twins are observed as well. Additionally, current forge...

International Nuclear Information System (INIS)

In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water to determine the irradiation-assisted stress corrosion cracking (IASCC) behavior of HTH Alloy X-750 and direct-aged Alloy 625. New data confirm previous results showing that high irradiation levels reduce SCC resistance in Alloy X-750. Heat-to-heat variability correlates with boron content, with low boron heats showing improved IASCC properties. Alloy 625 is resistant to IASCC, as no cracking was observed in any Alloy 625 specimens. Microstructural, microchemical and deformation studies were performed to characterize the mechanisms responsible for IASCC in Alloy X-750 and the lack of an effect in Alloy 625. The mechanisms under investigation are: boron transmutation effects, radiation-induced changes in ...

International Nuclear Information System (INIS)

(Dec 1970). United States Feeney, JA Boeing Co., Renton, Wash.

Science.gov (United States)

Ni-free shape memory alloys are promising functional materials for medical applications. A newly developed Ti-Mo based shape memory alloy shows superelasticity after thermomechanical treatment. However, the microstructure evolution and precipitation during thermomechanical processes are still not well understood. In the present paper, compressive deformation behavior at a series of temperatures of 298K - 973K and tensile deformation behavior of the alloy after aged at 573K - 973K have been investigated systematically. It is found that the compressive yield stress and ultimate compressive strength change with the deformation temperature. The ultimate tensile strength and yield stress of aged specimens also change with the aging temperature following a non-linear relationship. Microstructures of aged specimens as well as effects of lattice softening and aging-induced precipitates on ...

British Library Electronic Table of Contents (United Kingdom)

The effects of a modifier that contains Rare Earths (RE), low melting point alloy (Al-Bi-Sb) and Ca-Si alloy on an ultrahigh carbon steel containing 1.9wt.% C were studied. Microstructure characterization was carried out with optical microscopy (OM) and scanning electronic microscopy (SEM) combined with energy-dispersive spectrometry (EDS). Upon modification, the continuous eutectic carbide network structure was broken up and changed to a partly isolated and finer blocky structure in the as-cast alloy. Differential scanning calorimetry (DSC) revealed that the eutectoid temperature increased and the eutectic temperature decreased for the modified alloy. Modification also improved the impact toughness of the tempered steel, with a significant increase from 6.5 to 12.6Jcm^-^2, despite the har...

International Nuclear Information System (INIS)

An Al-5%Mg-0.18%Mn-0.2%Sc-0.08%Zr-0.002%Be was subjected to equal-channel angular extrusion up to true strains of #approx#3 and #approx#8, that resulted in the formation of partially recrystallized and fully recrystallized structure, respectively. It was shown that the alloy with partially recrystallized structure exhibits highest strength and ductility. The material with fully recrystallized structure showed lowest fatigue crack growth rate and highest value of fracture toughness. Reasons of this unusual effect of microstructure on crack propagation resistance under fatigue are discussed.

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An experimental verification for long-term performance of a Pd-Ag permeation in ITER tritium fusion cleanup units (FCU) is needed. In addition, information is required on the influence of tritium and {sup 3}He decay on the physical and chemical properties of Pd-Ag alloys (V-1). The results of the investigations of alloys (V-1) (mechanical properties and microstructure) after long-term usage exposition in tritium are given in this report. The experimental conditions (temperature, pressure, clearance, {sup 3}He concentrations) and the previous conclusions on the V-1 alloy performance are presented. (orig.).

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Constant extension rate (CERT) tests were performed on Alloy 690 and Alloy 800 nuclear steam generator tubing specimens. For the Alloy 690 specimens, tests were performed in deaerated 10% sodium hydroxide solutions at 315 deg C with a +100 mV applied potential. For the Alloy 800 specimens, tests were performed in deaerated 5% sodium hydroxide solutions at 343 deg C with no applied potential. The test specimens were machined from tubing which was produced by different manufacturing processes and in different heat treated conditions. The Alloy 690 tubing was tested in six different thermomechanical conditions, while the Alloy 800 tubing was tested in four different thermomechanical conditions. The results from the test program include a complete microstructural examination using light-optical and scanning electron microscopy. The CERT test ...

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Spiral orbit tribometry friction tests performed on Ni-rich Ni55Ti45 titanium ball bearings indicate that this alloy is a promising candidate for future aerospace bearing applications. Microstructural characterization of the bearing specimens was performed using transmission electron microscopy and energy dispersive spectroscopy, with NiTi, Ni4Ti3, Ni3Ti, and Ni2Ti4Ox phases identified within the microstructure of the alloy. Density functional theory was applied to predict the electronic structure of the NixTiy phases, including the band structure and site projected density of states. Ultraviolet photoemission spectroscopy was used to verify the density of states results from the density functional theory calculations, with good agreement observed between experiment and theory.

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Because noble dental casting alloys for metal ceramic restorations have a wide range of mechanical properties, knowledge of these properties is needed for rational alloy selection in different clinical situations where cast metal restorations are indicated. Purpose The purpose of this study was to compare the mechanical properties and examine both the fracture and polished surfaces of 6 noble casting alloys that span many currently marketed systems. Five alloys were designed for metal ceramic restorations, and a sixth Type GPT has Type IV alloy for fixed prosthodontics (Maxigold KF) was included for comparison. Material and methods Specimens (n=6) meeting dimensional requirements for ISO Standards 9693 and 8891 were loaded to failure in tension using a universal testin...

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The microstructural development and grain-coarsening behavior of WC-Co alloys, with and without a VC additive, were investigated. The primary goal was to determine the mechanism through which VC acts as a grain-growth inhibitor. The study involved long-time sintering experiments (1 to 100 hours) on fully dense material, nascent stage sintering (90 to 1,320 seconds) starting with the green compact, and surrogate liquid phase experiments to characterize the WC powder prior to sintering. Quantitative microstructural analysis using intercept length distributions was performed for the long-term sintering. The nascent stage experiments involved the measurement of the specific surface area (S{sub v}) of each type of interface separately allowing the determination of the contribution of each developing entity to the overall microstructural evolution. The VC addition has been found to enhance the breakup of ...

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The effect of warm rolling under various conditions on the microstructure and mechanical property was investigated using an AZ31 Mg alloy sheet. Several processing parameters such as initial thickness, thickness reduction by a single pass rolling, rolling temperature, roll speed, and roll temperature were varied to elicit an optimum condition for the warm rolling process of AZ31 Mg alloy. Microstructure and mechanical properties were measured for specimens subjected to rolling experiments of various conditions. Warm rolling of 30% thickness reduction per pass was possible without any side-crack at temperatures as low as 200 C under the roll speed of 30 m/min. The initial microstructure before rolling was the mixed one consisting of partially recrystallized and cast structures. Grain refinement was found to occur actively during the warm rolling, producing a very fine grain size of 7 ...

International Nuclear Information System (INIS)

Minor addition of B to the Ti-6Al-4V alloy reduces the prior #beta# grain size by more than an order of magnitude. TiB formed in-situ in the process has been noted to decorate the grain boundaries. This microstructural modification influences the mechanical behavior of the Ti-6Al-4V alloy significantly. In this paper, an overview of our current research on tensile properties, fracture toughness as well as notched and un-notched fatigue properties of Ti-6Al-4V-xB with x varying between 0.0 to 0.55 wt.% is presented. A quantitative relationship between the microstructural length scales and the various mechanical properties have been developed. Moreover, the effect of the presence of hard and brittle TiB has also been studied.

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A dilute tungsten heavy alloy consisting of 50W-35Ni-15Fe (wt pct) was liquid phase sintered at 1,500 C for times ranging from 30 to 960 minutes. This alloy corresponds to a nominal solid content of 20 vol pct at the sintering temperature. Because of the excess liquid, the alloy densified easily and exhibited extensive liquid-solid separation due to the density difference between the phases. The solid content at the compact bottom ranged from 45 to 70 vol pct over position and time. The microstructure of the settled region was quantified for volume fraction of tungsten, grain size, connectivity, and settled solid angle of repose. These results provide a basis for extending the microstructural parameters to possible microgravity conditions. The grain growth rate constant varies with the inverse 2/3 power of the volume fraction of liquid, possibly reflecting combined coalescence and ...

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Fine-grained AZ31 magnesium alloy sheets were prepared through hot rolling process. The superplastic properties of hot-rolled AZ31 Mg alloy was examined by uniaxial tensile tests at a temperature range 250{proportional_to}450 C and strain rate range 0.7 x 10{sup -3}{proportional_to}1.4 x 10{sup -1} s{sup -1}. Optical and scanning electronic microscope (SEM) were used to observe the microstructure evolution and fracture behavior in superplastic deformation of AZ31 Mg alloy and the values of deformation activation energy at various temperatures were calculated. It is demonstrated that, the hot-rolled AZ31 alloy begins to exhibit superplasticity from 300 C and a maximum elongation of 362.5% is obtained at 400 C and 0.7 x 10{sup -3} s{sup -1}. In the temperature range 300{proportional_to}400 C, the dominant superplastic deformation mechanism is grain boundary sliding (GBS) controlled by ...

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Magnesium cast parts as well as indirectly and hydrostatically extruded profiles were used in order to investigate the influence of different microstructures on the damping behaviour of magnesium AZ-alloys. Especially, hydrostatic extrusion leads to a significant grain refinement in the extruded profile compared to indirect extrusion. Strain dependent damping measurements were carried out at room temperature using alloys AZ31, AZ61 and AZ80. Damping was determined as the logarithmic decrement of free bending beam vibrations. The results of these measurements after indirect and hydrostatic extrusion are shown and discussed. (orig.)

International Nuclear Information System (INIS)

Thermohydrogen treatment effect on microstructure and mechanical properties is studied for a cast heat resistant pseudo-#alpha#-titanium alloy Ti-6242 (Ti-6Al-2Sn-4Zn-2Mo) widely used as a heat resistant material with operating temperature up to 500 deg C. It is shown that reversible hydrogen alloying is a promising alternative to thermomechanical treatment for transformation of (#alpha#+#beta#)-titanium alloy structure. The application of thermohydrogen treatment is noted to be of particular efficiency for shaped casting technology as it allows a noticeable increase of mechanical properties at a lower cost. The alloy after thermohydrogen treatment and subsequent heat treatment in the (#alpha#+#beta#) - range possesses high values of yield strength fatigue properties, creep resistance and has a satisfactory ductility. A consideration is also given to thermohydrogen treatment effect ...

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Magnesium alloys are ideal candidates to benefit from equal channel angular extrusion (ECAE) because of their poor forming characteristics due to a hcp structure. In this study, ECAE processing was applied to ZK31 and AZ31 magnesium alloys under various conditions. The grain size of as-ECAE specimens decreases with decreasing the processing temperature, however, the grain size decreases slightly with increasing number of repetitive processing. Both the tensile strength and 0.2% proof stress of as-ECAE specimens are high when processed at low temperature, but the elongation is high when processed at high temperature. Crystal orientation is different in the two alloys and it also varies according to the processing temperature for the two alloys. The difference of the crystal orientation influences the tensile properties, especially 0.2% proof stress. (orig.)

International Nuclear Information System (INIS)

The carbon transfer has been analyzed in the Alloy 800/sodium/stainless steel system by determining the carbon-uptake of Alloy 800 foils, which were exposed in liquid sodium of known carburizing potential. Under equilibrium condistions between 650 and 550_0C the measured total carbon concentrations in the Alloy 800 tabs were found to be roughly related to the carbon activities of the sodium environment by the equation already stated for the 18 Cr-8/10 Ni stainless steels, extrapolated to the chemical composition of the Ni-rich austenitic alloy. However the Alloy 800 was not found to undergo any decarburization in low-carbon activity environments. The carbon diffusion kinetics was determined as a function of temperature, it was found to be similar to that reported for the AISI-304 type of steel. The effects of sodium exposure on microstructural and mechanical ...

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Excimer laser processing enables both thermally-driven transformations and the incorporation of solutes into the surface of materials through melting and diffusional mixing. We have examined the effect of excimer laser processing on the microstructure and surface mechanical properties of titanium alloys. Changes in the surface hardness due to laser processing were studied using a Nanoindenter [trademark]. Alloying experiments using both mixing of evaporated surface layers of boron and laser gas alloying in air and in nitrogen all result in changes in the surface hardness of the material. Alloying with boron results in an amorphous surface which is somewhat harder than the as polished surface. Laser processing in air and pure nitrogen results in incorporation of oxygen and nitrogen and the development of fine ([approximately] 50 nm) precipitates of TiO and TiN respectively. ...

International Nuclear Information System (INIS)

In order to investigate the role of amorphous SiO2 particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO2 particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO2 was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO2 particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of ?-phase and amorphous nano-SiO2 particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO2 particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion ...

International Nuclear Information System (INIS)

Mixed microstructures have been studied in low- carbon microalloyed steels suitable for automotive applications, after continuous cooling from the hot-rolled condition. Microstructural features such as polygonal ferrite, bainitic and acicular ferrite and microphase constituent are identified using transmission electron microscopy. The influence of these mixed structures on the tensile strength, impact toughness and fracture behaviour is examined. It is found that improvements in impact toughness as compared with microalloyed medium- carbon ferrite/pearlite steels can be achieved from these predominantly acicular structures developed by controlling alloy composition and continuous cooling of these lower carbon steels. (orig.).

International Nuclear Information System (INIS)

Microstructure and properties of a Mg AZ31B laser beam weld without filler are studied using electron microscopy, X-ray diffraction and mechanical tests. The microstructure of the weld is characterized by a narrow heat affected zone, columnar grains and precipitate coarsening in the fusion zone. Texture in the fusion zone is significantly different from the texture of the base material. The residual stress distribution observed is similar at the top and the bottom of the weld, maximum tensile residual stress values are observed in the fusion zone. Tensile tests reveal differences in the mechanical behavior of the fusion zone and the parent material, which can be related to the differences of texture and the resulting deformation mechanisms.

International Nuclear Information System (INIS)

Microstructure characterization is important for controlling the quality of laser welding. In the present work, a detailed microstructure characterization by transmission electron microscopy was carried out on the laser welding cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft and an unambiguous identification of phases in the weldment was accomplished. It was found that there are #gamma#-FeCrNiC austenite solid solution dendrites as the matrix, (Nb, Ti) C type MC carbides, fine and dispersed Ni_3 Al #gamma#' phase as well as Laves particles in the interdendritic region of the seam zone. A brief discussion was given for their existence based on both kinetic and thermodynamic principles.

British Library Electronic Table of Contents (United Kingdom)

Vanadium carbide is the most effective grain growth inhibitor for ultrafine WC-Co composites due to its high solubility and mobility in the cobalt phase at relatively low temperatures; however, there are still some debates over the best way to introduce it into the WC-Co formulation. In this paper, the differences between admixed and chemically doped grain growth inhibitors on the microstructural development and properties of an ultrafine WC-10Co composite are discussed. The densification rate of chemically doped samples is slower in the early stage of sintering and the WC grain sizes of the sintered alloys are finer than those of admixed samples, leading to the increase of hardness and transverse rupture strength of the sintered alloys. The effectiveness of the chemically doped inhibitor ...

International Nuclear Information System (INIS)

In the paper results of the investigation on the effect of microstructure on room temperature tensile properties and fracture toughness of two-phase #alpha#+#beta# titanium alloy Ti-6Al-2Mo-2Cr have been presented. Microstructure has been varied by changes in the cooling rate from the solution treatment temperature and aging time and temperature. Mechanical properties examined show dependence on the treatment conditions, especially aging conditions. It has been attributed mainly to the amount and morphology of #alpha# phase obtained after heat treatment. The higher volume fraction of lamellar #alpha# structure, the higher fracture toughness. (author)

Energy Technology Data Exchange (ETDEWEB)

Materials and processing designs for advanced magnesium alloys with fine microstructures and superior properties were established by the combination of the repeated plastic working and the Mg{sub 2}Si synthesis in solid-state. The grain size was less than 1 {mu}m via RPW process due to its severe plastic working on raw powder. The hot extruded magnesium alloys produced in industries showed high ultimate tensile strength, e.g. 420{proportional_to}450 MPa, when employing Mg-Zn-Al-Ca-RE (Rare Earth) alloy coarse powder, having 0.5{proportional_to}2 mm diameter, as input materials. (orig.)

International Nuclear Information System (INIS)

An alloy of composition Ti-4.4 wt.% Ta-1.9 wt.% Nb is being developed as a structural material for corrosion applications, as titanium and its alloys possess excellent corrosion resistance in many oxidizing media. The primary physical metallurgy database for the Ti-4.4 wt.% Ta-1.9 wt.% Nb alloy is being presented for the first time. Determination of the #beta# transus, M_s temperature and classification of the alloy have been carried out, employing a variety of microscopy techniques, X-ray diffraction (XRD), micro-hardness and differential scanning calorimetry (DSC). The #beta# transition temperature or #beta# transus determined using different experimental techniques was found to agree very well with evaluations based on empirical calculations. Based on chemistry and observed room temperature microstructure, the alloy has been classified as an #alpha# + #beta# ...

International Nuclear Information System (INIS)

Ti-15Mo-2.7Nb-3Al-0.2Si (Timetal-21S), a metastable #beta#-titanium alloy, is a candidate material for titanium matrix composite structures in hydrogen-fueled hypersonic planes because of its excellent formability and adequate mechanical properties in the 500--800 C temperature range. The alloy is strengthened through the precipitation of fine #alpha# particles in the #beta# matrix. The mechanical properties and microstructures are controlled by a solutionizing/aging heat treatment. A major concern in using titanium alloys in hydrogen service is the embrittlement caused by the precipitation of hydrides. It is believed that the large solubility of hydrogen in the #beta#-phase would preclude the precipitation of hydrides in Beta titanium alloys, especially at low hydrogen pressures. However, depending on the hydrogen content, a shift in the ductile/brittle transition temperatures to ...

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Proposed ductile fracture toughness parameters from tensile tests have been successfully used to determine the post-weld heat treatment temperature for an alloy 800/(9Cr-1Mo) steel dissimilar metal weld joint that is optimum with respect to accelerated aging, which simulates service conditions. This approach proved superior to using microstructural analysis, microhardness profiles, and conventional tensile properties. (author).

International Nuclear Information System (INIS)

Three ternary austenitic alloys (Fe-15Cr-25Ni, Fe-15Cr-25Ni-0.04P, Fe-15Cr-45Ni in both annealed and cold worked conditions) were irradiated at 465 C to 0.15, 0.28, and 0.42 dpa at above core position in the Fast Flux Test Facility utilizing the Materials Open Test Assembly to study the separate and synergistic effects of He/dpa ratio, phosphorus addition, nickel content and cold work level on microstructural evolution and hardening. The helium/dpa ratio was varied by isotopic doping with "5"9Ni to enhance the production rate of helium. The helium production rate was evaluated to be 62 appm He/dpa in the "5"9Ni-doped specimens and 0.26 appm He/dpa in the undoped specimens. Transmission electron microscopic examinations revealed that alloy composition affected significantly the evolution of microstructure during irradiation. Phosphorus addition prevented the formation of Frank loops through the ...

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Flow-curve characteristics of the heat-resistant steels X 20 CrMoV 12.1 and alloy 800 (X5NiCrTiAl32.20) were measured by tensile and compression tests at temperatures between room temperature and 800 C and strain rates {epsilon}{<=}10 s{sup -1} in connection with microstructure investigations (dislocation content, carbide precipitation) by TEM and X-ray diffraction analysis (XDA). Modelling the deformation behaviour of the steels in terms of the microstructure development indicates that it cannot be explained in a simple manner. The flow curves {sigma}={sigma}({epsilon}, {epsilon}, T) lie, in general, between those predicted by the Kocks-Mecking-Estrin model and a modified (i.e. two-parameter) Roberts model. Because of the less complicated nature of the deformation process the correspondence of experiment and modelling is more satisfying in the case of the material X 20 CrMoV 12.1. (orig.) 26 refs.

International Nuclear Information System (INIS)

A new metastable beta titanium alloy, Beta-CEZ, has been developed by CEZUS. This alloy was designed for use at moderate temperatures up to 450 C (840 F). Alloy requirements also included high mechanical strength, high fracture toughness and improved creep resistance as compared to existing beta alloys. The understanding of the relationships between processing/microstructure/mechanical properties in the alloy may lead to applications of such promising material in current and future airplanes. In this study, a combination of several forging routes, which included through-transus, hot-die and warm-die forging, with subsequent heat treatments were selected in order to evaluate the microstructure-mechanical property relationships. It was found that the recrystallized prior beta grain boundary alpha, characteristic of the through-transus forging ...

International Nuclear Information System (INIS)

Application of Alloy 800 in steam generator tubing of fast reactors, where continuous service temperature of the order of 550"0C is experienced, has been analyzed with respect to small variations in its chemical composition. Several laboratory melts of Alloy 800 have been prepared and their microstructural and mechanical property changes during simple aging and creep tests at 500 to 600"0C have been studied. It has been found that in the above temperature range precipitation of M_2_3C_6 on the grain boundaries is independent of the Ti : C ratio generally specified for Alloy 800. Gamma prime precipitation occurred in alloys containing as low as 0.5 percent Ti + Al after 1000 h of aging and was accompanied with a creep ductility decline. Upon #gamma# precipitation creep rate was retarded and its reacceleration for test times up to 8500 h at 550"0C was not observed. Based on the ...

International Nuclear Information System (INIS)

A study was made into microstructure and texture of cold rolled titanium alloy VT-35 with various hydrogen content aimed to reveal hydrogen influence on the mechanism of cold plastic deformation by rolling. Experiments were carried out using sheets 1.2 mm thick hydrogenated up to hydrogen concentrations from 0.06 to 0.554 mass. %. All specimens constituted a single-phase FCC #beta#-solid solution. It is shown that small hydrogen additions have a plasticizing effect on #beta#-titanium alloys in their cold rolling. The character of texture is dependent on hydrogen concentration and determined by deformation mechanism. 6 refs.; 5 figs.

International Nuclear Information System (INIS)

Effect of low-frequency pulsating magnetic field on the microstructure and magnetic properties of amorphous alloy Fe_7_8Si_9B_1_3 were investigated. The temperature rise induced by the treatment was measured by a non-contact infrared thermometer. The crystallization behavior and microstructure of specimens were studied by Moessbauer spectroscopy and transmission electron microscope (TEM). Magnetic properties of the specimens were investigated by alternating gradient magnetometer (AGM). The results show that the low-frequency pulsating magnetic field can promote the single-phase crystallization of amorphous alloy Fe_7_8Si_9B_1_3. The frequency, f of applied field is from 10 to 40 Hz, magnetic field, H is from 0.02 to 0.04 T and treatment duration, t is from 180-300 s. The volume fraction of crystallization phase (#alpha#-Fe(Si), the grain size, 2-10 nm) is 3-7%. The temperature rise less than 7 deg. C. ...

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Powders with nominal compositions (in atomic percent) Ti-48Al and Ti-48Al-2Nb-2Cr were prepared by the plasma rotating electrode process (PREP) and gas atomization (GA) techniques. As-solidified and heat-treated (1000degC per 3 h) powder samples were examined by metallography, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The microstructures of the powders were characterized as a function of atomization technique, alloy content, powder particle size (solidification rate) and thermal history. All of the as-solidified powders were comprised of disordered [alpha], and ordered [alpha][sub 2]-Ti[sub 3]Al and [gamma]-TiAl. For both alloys, a larger volume fraction of [alpha] and [alpha][sub 2] was observed in the PREP powders relative to GA powders of comparable size. Additionally, for both alloys and both atomization techniques, the volume fraction of [alpha][sub 2] ...

International Nuclear Information System (INIS)

Past elastic-plastic fracture studies for leak-before-break (LBB) assessment of low alloy steel pipings have been focused mostly on the behavior of base metals and their weld metals. In contrast, the heat-affected zone (HAZ) of a welded pipe has not been studied in detail primarily because the size of the HAZ is too small to make specimens for mechanical properties measurements. In this study, microstructural analyses, microhardness tests, tensile tests and J-R tests have been conducted as a function of distance from a fusion line and temperature for HAZ materials of SA106Gr.C low alloy piping steels. For the ferrite-pearlite steels such as SA106Gr.C, the HAZ specimens showed a higher yield strength and fracture toughness compared with those of its base metal. These characteristics, despite of grain coarsening, can be explained by cleaner microstructures of HAZ materials with a finer morphology of ...

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Transmission electron microscopy studies on solution-annealed Alloy 800 revealed small (100-200 nm), spherical-shaped titanium carbide (face centered cubic structure) and large (200 nm-5 {mu}m), faceted titanium nitride (hexagonal structure) particles randomly distributed in the austenite matrix. The volume fraction of former particles was found to be greater than that of the latter. Corrosion studies of the alloy in acidic, chlorides and acidic chloride environments at room temperature indicated that the passivity of Alloy 800 was adversely affected by the addition Cl{sup -} ions. X-ray photoelectron spectroscopy revealed that the surface film formed on the alloy at the onset of passivity consisted of Cr{sup 3+} (as Cr{sub 2}O{sub 3}), without any Fe{sup 3+}/Fe{sup 2+} or Ni{sup 2+}. Scanning electron microscopy studies indicated initiation of pitting at large, faceted particles, not at small, ...

International Nuclear Information System (INIS)

The influence of some processing factors such as cold work and heat treatment on the susceptibility to caustic stress corrosion cracking (SCC) of modified alloy 800, referred to alloy 800 M, in a boiling solution of 50%NaOH + 0.3%SiO_2+0.3%Na_2S_2O_3 was investigated by means of microstructure examination, tensile test, stress analysis, SCC test of C-rings, Auger electron spectroscopy (AES) and corrosion mode. Cold work led to lengthening of grains, decrease in ductility, increase in strength, residential stress and susceptibility to SCC. With increasing temperature of heat treatment on alloy 800 M after cold work, grains became bigger, ductility increased but strength, residential stress and susceptibility to SCC decreased. SCC cracks on C-ring specimens initiated from pitting and propagated along grain boundaries. AES analysis indicates that the surface films on alloy 800M are ...

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Car weight corresponds directly to fuel consumption and driving performance. So in order to improve the fuel efficiency and performance of a car the weight has to be reduced. Magnesium as a light metal offers a wide range of weight saving opportunities, especially Magnesium wrought alloys with their improved mechanical properties have a high potential for structural applications. Mechanical properties in terms of their quality and anisotropy are dependent on the microstructure of the material and can be characterized by their degree of inhomogeneity, their grain size distribution and their crystallographic texture. Therefore the orientation distribution of grains, the grain size, its size distribution, the chemical composition (precipitates) itself influence the mechanical parameters and their anisotropy. In this presentation first results of mechanical anisotropy are given: differences in yield stress, r-values and their relation to the ...

International Nuclear Information System (INIS)

The effect of phosphorus on the corrosion resistance of Al-bronzes is studied in detail in this work. A literature review showed that there are a lot of things known about the microstructure and the mechanical properties of Al-bronzes. In spite of their corrosion resistance the corrosion properties and the structure of the protective oxide films of Al-bronzes were seldom a matter of interest. Systematic studies of the influence of different alloying elements on the oxide film and the corrosion properties are rare. Therefore, it is not possible to predict the corrosion resistance of Al-bronzes, made by alloying particular elements. The high corrosion resistance of the new alloy CuAl_2_0P_1 was the reason to investigate the influence of phosphorus on the corrosion properties of Al-bronzes in more detail. A systematic study of the microstructure and the corrosion properties of Cu, ...

International Nuclear Information System (INIS)

Nanocrystalline cemented tungsten carbide has attracted considerable interests for use in cutting tool because of its superior mechanical properties. In this study, nano-sized powders of mixed WC and Co were prepared from attrition-milled oxides by a gas reduction-carburization process. The effects of compacting pressure, heating schedule, additional ball-milling, and the presence of a grain growth inhibitor on the sintering properties of the nano-sized WC-Co powders were examined. The grain size and phases in WC-Co alloy were clearly affected by compacting pressure. Because of the trapped gases and the lower melting point of the cobalt binder, when a compact of nano-sized WC-Co powder was sintered through a heating schedule with holding steps, the sintered alloy maintained the small size of WC grains without any #eta# phase. In addition, the additional ball-milling improved the microstructure and mechanical properties of ...

British Library Electronic Table of Contents (United Kingdom)

The nanocomposite WC-Co powders were prepared through planetary ball milling method. Effects of grain growth inhibitor addition and the vacuum sintering parameters on the microstructure and properties of ultrafine WC-10Co cemented carbides were investigated using X-ray diffractometer, scanning electron microscope and mechanical property tester. The results show that VC and NbC additions can refine the WC grains, decrease the volume fraction of Co3W3C phase in ultrafine WC-10Co cemented carbides, and increase the hardness and fracture toughness of the base alloys. After sintering for 60 min at 1400 degreeC, the average grain size and hardness of ultrafine-grained WC-10Co-1VC cemented carbide are 470 nm and HRA 91.5, respectively. The fracture toughness of cemented carbide WC-10Co-1NbC alloy...

International Nuclear Information System (INIS)

Metastable austenitic steels show excellent mechanical properties, such as high strength combined with excellent ductility and toughness due to martensitic transformation under mechanical loading (transformation induced plasticity effect). A good energy consumption, and, in the case of high-alloyed metastable austenitic steels, a high corrosion resistance, increase the potential of these materials for diverse applications, also in regard of safety requirements. Up to now, numerous wrought alloys were investigated concerning mechanical behaviour, TRIP-effect, martensitic transformation behaviour and modelling of transformation kinetics or stress-strain behaviour. New high alloyed cast CrMnNi-steels, developed at Technical University Bergakademie Freiberg, provide the chance to reduce processing steps, production time and costs. In order to understand the influence of temperature on the martensitic phase transformation ...

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A 9Cr-1Mo steel with properties improved over other ferritics in the ranges from 9 to 12% Cr and 1 to 2% Mo and over the widely used 2 1/2 Cr-1Mo steel has recently been developed. The main changes in the modified alloy, compared with the standard alloy, include: addition of niobium and vanadium, to improve the alloy's elevated-temperature strength properties; a specified range for each element; and a specification for nitrogen, which is not listed for the standard 9Cr-1Mo. Microstructural work has indicated that the improved strength of the modified alloy comes from two factors: (1) fine M/sub 23/C/sub 6/ precipitate particles nucleate on Nb/C, N, which comes out first during the heat treatment; and (2) the vanadium enters M/sub 23/C/sub 6/ and retards its growth at the service temperature. Mechanical properties discussed were Charpy-impact, tensile, and creep properties. ...

British Library Electronic Table of Contents (United Kingdom)

Laser consolidation (LC) developed by National Research Council???s Industrial Materials Institute (NRC-IMI-London) since mid-1990s, is a laser cladding based rapid manufacturing and material additive process that could fabricate a ???net-shape??? functional metallic shape through a ???layer-upon-layer??? deposition directly from a computer aided design model without using molds or dies. In order to evaluate the LC processability of different materials, some representative nickel-based superalloys (IN-625, IN-718, IN-738, and Waspaloy), stainless steels (austenitic SS316L and martensitic SS420), and lightweight alloys (Ti???6Al???4V titanium alloy and Al-4047 aluminum alloy) have been investigated. Like other laser cladding based processes, due to process-induced rapid directional solidifi...

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Two rapidly solidified powders with compositions Al-6.7 wt.% Fe-5.9 wt.% Ce and Al-6.2 wt.% Fe-5.9 wt.% Ce-1.63 wt.% Si were separated into -32 [mu]m and +32 to -63 [mu]m size fractions. Powders from both size fractions were extruded at 500 C. For comparison purposes, extrusion at a lower temperature of 400 C was also performed. In this investigation, tensile property evaluation indicated that processing of finer size fractions at high temperature offers no advantages in terms of the tensile properties but is advantageous in terms of improving the fracture toughness of alloy B. These observations underline the importance of the stability of powder microstructure during thermomechanical processing for the development of optimum mechanical properties. (orig.)

British Library Electronic Table of Contents (United Kingdom)

We present a novel fabrication route yielding Raney-platinum film electrodes intended as glucose oxidation anodes for potentially implantable fuel cells. Fabrication roots on thermal alloying of an extractable metal with bulk platinum at 200^oC for 48h. In contrast to earlier works using carcinogenic nickel, we employ zinc as potentially biocompatible alloying partner. Microstructure analysis indicates that after removal of extractable zinc the porous Raney-platinum film (roughness factor ~2700) consists predominantly of the Pt3Zn phase. Release of zinc during electrode operation can be expected to have no significant effect on physiological normal levels in blood and serum, which promises good biocompatibility. In contrast to previous anodes based on hydrogel-bound catalyst particles the ...

British Library Electronic Table of Contents (United Kingdom)

Ceramic coatings with high emission were fabricated on Ti6Al4V alloy by microarc oxidation (MAO) with additive FeSO4 into the electrolyte. The microstructure, chemical composition and chemical state of the coatings were determined by SEM, XRD, EDS and XPS, respectively. The bonding strength between the coating and substrate was studied by tensile strength test, together with the thermal shock resistance of the coating. The results showed that Fe content in the coating layer significantly affect its thermal emissivity. The relative content of Fe in the coatings surface increased at first and then decreased with increasing the concentration of FeSO4 in electrolytes, so does the emissivity of the coatings. The bonding strength became weaker with increasing the concentration of FeSO4. In addit...

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The effects of antimony addition on the microstructures and creep behavior of AZ31 have been studied. Constant load creep tests were carried out at 200 C and an initial stress of 50MPa for AZ31 alloys containing antimony up to 0.84% by weight. Results show that Small additions of antimony to AZ31 effectively decreased the creep extension and steady state creep rates. The steady state creep rate of AZ31 was reduced 2.5 times by the addition of 0.84% of antimony by weight. The main reason for the higher creep resistance is due to the presence of high volume fraction ({proportional_to} 20%) of second phases including Mg{sub 3}Sb{sub 2}, which effectively hindered the movement of dislocations during the elevated temperature creep. (orig.)

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Water model experiments were conducted to develop a two-stage stirring method for obtaining higher yields and a more uniform distribution of graphite particles in copper alloys. This was followed by several melts for synthesis of copper-graphite alloys in which Ti was used as a wetting agent to improve the wettability of graphite in the copper melt. In the first stage, a vortex method was employed to facilitate the addition of graphite particles into the copper melt. In the second stage, a specially designed stirrer was used for uniform particle distribution while avoiding the formation of vortex in the melt. The two-stage stirring was found to considerably improve the recovery of graphite, over those obtained with the prior practice of single-stage stirring and resulting in a more uniform particle distribution. In addition, graphite recoveries increased with increasing Ti content in the range investigated. Floatation, fluidity, and directional ...

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The microstructures of magnesium AZ31 are examined following hot compression testing and annealing. The grain size, fraction dynamically recrystallized and, in a couple of cases, the crystallographic texture are reported. It was found that the progress of dynamic recrystallization is strongly sensitive to processing conditions but that the dynamically recrystallized grain size was less sensitive to stress than in other metals. It was also found that, for structures containing between 80 and 95% dynamic recrystallization, abnormal grain growth occurs during annealing. The crystallographic texture produced is also sensitive to the deformation conditions. (orig.)

International Nuclear Information System (INIS)

Growing competitiveness of alternative manufacturing routes requires cost minimization in the production of drop forged components. The authors analyse the potential of medium carbon, vanadium microalloyed steels for drop forging. Laboratory and industrial experiments have been carried out emphasizing deformation and temperature cycles, strain rates and dwell times showing a typical processing path, associated mechanical properties and corresponding microstructures. The steels the required levels of mechanical properties on cooling after forging, eliminating subsequent heat treatment. The machinability of V-microalloyed steels is also improved when compared with plain medium carbon steels. (author)

International Nuclear Information System (INIS)

The present study has examined for #alpha#/#beta#-Ti alloys the relationship between the morphology and crystallography of Widmanstaetten plates of #alpha#-Ti in colonies within a prior grain of #beta#-Ti. Thus, optical metallography, scanning electron microscopy and transmission electron microscopy have been used to characterize the morphological features of the microstructure, whereas orientation-imaging microscopy (OM) and transmission electron microscopy (TEM) have been employed to reveal crystallographic information. It has been discovered that within a prior #beta#-Ti grain, although the growth direction of the Widmanstaetten plates in given colonies may differ by large angles from #alpha#-plates in other colonies, they may exhibit very close crystallographic relationships. For example, inclined #alpha#-plates may share common basal planes and be related by a rotation of #approx#10.5 deg. about the c-axis of the crystals. This phenomenon ...

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The Ti-6Al-4V alloy was treated by inductively coupled rf plasma nitriding. The effects of plasma-processing time in the range of 5-35 min on the microstructure and the mechanical properties of the plasma-nitrided Ti-6Al-4V samples were studied. The plasma power input was adjusted at 450 W and pure N{sub 2} gas was introduced to establish a treatment pressure of 8.0-8.4 x 10{sup -2} mbar. The characteristics of the nitrided layers have been investigated by microhardness testing, surface roughness measurements, optical microscopy, and x-ray diffraction. The results show that the surface microhardness increases as the plasma-processing time increases to reach 2000 HV0.1 at a plasma-processing time of 35 min. A high nitriding rate of 2.81 {mu}m{sup 2} s{sup -1} at a plasma-processing time of 25 min was achieved. The formation of the hard phases TiN, Ti{sub 2}N, and Ti(N) in the Ti-6Al-4V surfaces are found to be the reason for the increased ...

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Micron-size Ni-base alloy (NBA) powders were mixed with both 1.5 wt.% (hereinafter %) micron-size CeO{sub 2} (m-CeO{sub 2}) and also 1.5% and 3.0% nano-size CeO{sub 2} (n- CeO{sub 2}) powders. These mixtures were coated on low-carbon steel (Q235) by 2.0 kW CO{sub 2} laser cladding. The effects on the microstructures, phases and electrochemical corrosion of the coatings upon the addition of m- and n- CeO{sub 2} powders to NBA (m- and n- CeO{sub 2} /NBA) have been investigated. The results showed that a smooth coating was prepared under suitable processing parameters (P= 2.0 kW, V= 180 mm min{sup -1}) by adding 1.5% n- CeO{sub 2}. In addition to the primary phases of {gamma}-Ni, Cr{sub 23} C{sub 6} and Ni{sub 3} B in the Ni-base alloy coating, CeNi{sub 3} was formed in Ni-base alloy coatings with both n- CeO{sub 2} and m-CeO{sub 2} particles, and CeNi{sub 5} appeared in the coating upon decreasing the ...

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Modern commercial alloys are not suited for future steam turbines of operating temperatures beyond 700 C. {gamma}'-hardened alloys like Waspaloy have good mechanical characteristics but have defects when large batches are melted. {gamma}'/{gamma}''-hardened alloys like Inconel 706, on the other hand, are easy to produce but have insufficient microstructural long-term stability and insufficient creep strength. Mixed crystal solidified alloys like Inconel 617 have excessive yield stress at forging temperatures. Two new alloys were therefore developed. Results so far show that they have good production characteristics but insufficient mechanical characteristics. The reasons for this are currently under investigation. (orig.) [German] Die heutigen kommerziellen Legierungen sind nicht geeignet fuer den Einsatz in zukuenftigen ...

International Nuclear Information System (INIS)

The creep characteristics of alloy 800 at temperatures around 600"0C are greatly affected by the composition and treatments in the final stages of manufacture. Short-term and creep properties of alloy 800 at 600"0C are described for six melts covering the carbon range 0.054-0.078%, the titanium range 0.23-0.57% and the aluminium range 0.17-0.52%. The properties are related to the alloy chemistry and the microstructure. It is shown that homogeneously nucleated #gamma#'-precipitates are the main cause of low ductility in alloy 800 but there is also some influence of, for instance, grain boundary M_2_3C_6 films and discontinuous precipitation of Ni_3Ti or M_2_3C_6 in grain boundaries. The extent of #gamma#'-precipitation is controlled primarily by the (Ti+Al)-content. To avoid #gamma#' and ensure a high creep ductility the (Ti+Al)-content should be limited to 0.70-0.75% for ...

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The purpose of our research program is to understand the influence of elastic misfit strain and applied stress on the development of microstructure in two-phase coherent alloys. The long-term goal of our research is to identify those material parameters that promote microstructural stability in multiphase systems at elevated temperatures. Our efforts since the last progress report in February 1991 have been twofold. First, we have continued performing coarsening simulations of elastically and diffusionally interacting particles in an infinite matrix. In addition, we have been performing simulations of unstressed systems during coarsening. Secondly, we have begun to develop an experimental component to the research that would allow a careful comparison between theory, computer simulations and experiment. We have continued to focus our computer simulations of stressed systems on elastically homogeneous and isotropic systems ...

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Alumina (94 and 99.8% grade compositions) was brazed directly to itself with gold-based active brazing alloys (ABA's) containing vanadium additions of 1,2 and 3 weight percent. The effects of brazing conditions on the joint properties were investigated. Wetting behavior, interfacial reactions, microstructure, hermeticity and tensile strength were determined. Wetting was fair to good for the ABA and base material combinations. Microanalysis identified a discontinuous Al-V-O spinel reaction product at the alumina-braze interface. Tensile strength results for 94% alumina were uniformly good and generally not sensitive to the vanadium concentration, with tensile values of 85-105 MPa. There was more variability in the 99.8% alumina strength results, with values ranging from 25-95 MPa. The highest vanadium concentration (3 wt. %) yielded the highest joint strength for the brazed 99.8% alumina. Failures in the 99.8% alumina samples occurred ...

Science.gov (United States)

In this study, four API X80 pipeline steels were fabricated by varying Mo, Cr, and V additions, and their microstructures and crystallographic orientations were analyzed to investigate the effects of their alloying compositions on tensile properties and Charpy impact properties. Because additions of Mo and V promoted the formation of fine acicular ferrite (AF) and granular bainite (GB) while prohibiting the formation of coarse GB, they increased the strength and upper-shelf energy (USE) and decreased the energy transition temperature (ETT). The addition of Cr promoted the formation of coarse GB and hard secondary phases, thereby leading to an increased effective grain size, ETT, and strength, and a decreased USE. The addition of V resulted in a higher strength, a higher USE, a smaller effective grain size, and a lower ETT, because it promoted the formation of fine and homogeneous of AF and GB. The steel that contains 0.3 wt pct Mo and 0.06 wt ...

International Nuclear Information System (INIS)

A personal computer based single specimen unloading technique has been demonstrated using a nuclear grade pressure vessel material, A533B Class I steel, and an #alpha#-#beta# titanium alloy, CORONA-5. Experimental parameters investigated in the case of steel include the effect of test temperature, loading rate and neutron irradiation. Results revealed the effect of dynamic strain aging (DSA) as a drop in the critical crack initiation fracture toughness (Jsub(q)); the minimum in Jsub(q) shifts to higher temperatures at higher test speeds as predicted from DSA models. In CORONA-5, the effects of microstructure and heat treatment for two different sizes of equiaxed #alpha# morphology in a #beta#-matrix heat treated to different yield strengths were investigated. It is found that the observed higher values of Jsub(q) and tearing modulus result from a greater tortuosity of the crack path and ease of crack blunting. The largest increase in Jsub(q) ...

International Nuclear Information System (INIS)

Post-irradiation annealing was used to help identify the role of radiation-induced segregation (RIS) in irradiation-assisted stress corrosion cracking (IASCC) by preferentially removing dislocation loop damage from proton-irradiated austenitic stainless steels while leaving the RIS of major and minor alloying elements largely unchanged. The goal of this study is to better understand the underlying mechanisms of IASCC. Simulations of post-irradiation annealing of RIS and dislocation loop microstructure predicted that dislocation loops would be removed preferentially over RIS due to both thermodynamic and kinetic considerations. To verify the simulation predictions, a series of post-irradiation annealing experiments were performed. Both a high purity 304L (HP-304L) and a commercial purity 304 (CP-304) stainless steel alloy were irradiated with 3.2 MeV protons at 360 deg. C to doses of 1.0 and 2.5 dpa. Following irradiation, ...

Energy Technology Data Exchange (ETDEWEB)

Alloying elements such as Fe and Cr are generally considered to be effective even in small quantities for corrosion resistance of Zircaloy-4. The maximum total solubility of Fe + Cr in a Zr-Sn matrix has been reported to be very low. Therefore, most of these elements are observed in the form of ternary Zr-Fe-Cr-type precipitates. To clarify the effects of precipitates on corrosion property, Zr-1.3 Sn-(Fe,Cr) alloys containing Fe + Cr from 45 up to 180 ppm (the Fe to Cr ratio is about 2) were melted from pure zirconium (X-bar Zr and EB-Zr) and pure alloying elements. They were subjected to corrosion testing in 633 K water and microstructural analysis. It was found that precipitate-free materials showed much larger weight gains than precipitate-containing materials even at the same alloy compositions. Subsequently, a corrosion test on the precipitate-free material galvanically coupled ...

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The properties of AlN make this material very attractive for optical, electronic, and tribological application. Also, if the AlN could be formed on the Al surface to enhance its surface properties, Al could be applied for the lightening of machine parts. However, a dense oxide film exists on the surface of Al, which prevents the formation of the Al nitride even during plasma nitriding and plasma coating process. In this study, plasma nitriding has been tried to form an AlN layer on Al after the surface activation processes. During the plasma nitriding, the density of the nitrogen ions was amplified by means of controlling the power of the Al substrates. The film thickness, microstructural features and the mechanical properties such as hardness and wear properties of the AlN layer were examined as a function of the process parameters of pretreatment and plasma nitriding

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To clarify the mechanism of plasma nitriding, the authors examined the optical microstructure, the hardness, the precipitation, and the concentration of dissolved nitrogen in Fe-18Cr-9Ni nitrided using plasma in the range of 723-823 K. Compared with ammonia-gas nitriding, the features of plasma nitriding are the formation of small chromium-nitride precipitates (CrN), the absence of an externally nitrided layer, the high concentration of dissolved nitrogen, and the high hardness (HV = 1,200). The diffusion coefficient of nitrogen in the present alloy was determined using the growth rate of the internally nitrided layer, based on calculations used in internal oxidation. Plasma- and gas-nitriding were also compared with respect to the growth rate of the nitrided layer.

British Library Electronic Table of Contents (United Kingdom)

The aim of this study was to develop a nanostructured Nb2O5-natural hydroxyapatite bulk composite to serve as an alternative biocompatible bulk material for implants. A set of samples of hydroxyapatite from fish bones with different concentrations of Nb2O5 were designed. They were prepared through a milling process, compacted under different pressures (350, 450, 550 and 650MPa) and sintered in air atmosphere at 1000^oC for 1h. The results revealed that the prepared composites presented strong interactions between the two elements and showed improvement in the sinterability with significant densification and microstructure changes, suggesting that they are promising for implants meant to replace bone tissues.

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The influence of plasma nitriding on the fatigue behaviour of AISI 4140 low-alloy steel was investigated under varying process conditions of temperature (500-600 C), time (1-12 h), heat treatment before ion nitriding (quenched and tempered, normalized) and gas mixture (50% H{sub 2}-50% N{sub 2}). A rotating bending fatigue machine was used to determine the fatigue strength. It was found that the plasma nitriding improves the fatigue strength and increases the fatigue limit depending on the surface hardness of the case depth. The microstructure of surface and diffusion layers was examined by optical microscopy. The fracture surface of specimens and the origin of fatigue cracks were observed by scanning electron microscopy.

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In order to enhance the mechanical properties of magnesium alloy (AZ31) sheet, an integrated sheet-making process including billet casting, extrusion and rolling was attempted. Microstructural analysis was carried out and the mechanical properties at each processing step were also investigated by tensile tests. By an extrusion process of ingot-processed billet, average grain size of billet was reduced from 91.2 to 28.2 {mu}m, and a further reduction in grain size to 16.9 {mu}m was obtained by subsequent rolling of extruded 5 mm thin slab. In the final step, a rolled sheet of 1 mm showed a remarkable refinement in grain size down to 8.8 {mu}m. Regarding mechanical properties, tensile strength and elongation for as-cast billet, as-extruded thin slab and as-rolled sheet increased from 189, 258 to 234 MPa, and from 13, 16.5 to 23%, respectively. (orig.)

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Microstructure evolution under hot deformation was investigated in compression of a magnesium alloy AZ31 at 673 K (0.73T{sub m}). Two kinds of samples were machined along the parallel and transverse direction of the extruded rods. New fine grains are evolved at corrugated grain boundaries at low strains and developed rapidly in grain interiors in the medium range of strain, finally leading to a roughly full evolution of equiaxial fine grains. Kink bands are evolved at corrugated grain boundaries and in grain interiors at low strains. The boundary misorientation of kink band increases rapidly with increasing strain. These characteristics of new grain evolution process are not changed by the orientation of the samples, while the flow behaviors clearly depend on it. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction resulting in grain fragmentation by kink bands, i.e. continuous dynamic ...

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The topics of these short lectures on the subject of cyclic stress were: Microstructural mechanisms of damage accumulation under a multistage cyclic stress until incipient cracking; influence of surface decarbonizing phenomena on the failure behaviour of steel construction parts subjected to cyclic stress; thermocyclic fatigue of pipe samples of austenitic steel 1.4436; studies on surface structuring, microstructure and fatigue in LCF area. The short lectures on effects of quasi-static and creep stress were: Shear fracture in AlMg alloys as a result of local plastic instability; study of formation and growth of pores for an early recognition of damage and the course of damage in heat-resistant steels under creep test; experimental and numeric studies of the infuence of the microstructure on the course of damage during shear fractures of steel; numerical modelling of ductile fractures on the basis of ...

International Nuclear Information System (INIS)

Exploratory experiments of laser welding cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft were conducted. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. The corresponding mechanisms were discussed in detail. Results showed that the laser-welded seam had non-equilibrium solidified microstructures consisting of FeCr_0_._2_9Ni_0_._1_6C_0_._0_6 austenite solid solution dendrites as the dominant and some fine and dispersed Ni_3Al #gamma#' phase and Laves particles as well as little amount of MC short stick or particle-like carbides distributed in the interdendritic regions. The average microhardness of the welded seam was relatively uniform and lower than that of the base metal ...

International Nuclear Information System (INIS)

The effect of electron beam welding parameters on fusion zone (FZ) microstructure and porosity in a Ti-6.8 Al-3.42 Mo-1.9 Zr-0.21 Si alloy (Russian designation VT 9) has been investigated. It has been observed that the FZ grain width increased continuously with increase in heat input when the base metal was in the #beta# heat-treated condition, while in the #alpha# + #beta# heat-treated base metal welds, the FZ grain width increased only after a threshold energy input. The difference is attributed to both the weld thermal cycle and the pinning effect of equiaxed primary alpha on grain growth in the heat-affected zone (HAZ) of #alpha# + #beta# heat-treated base metal. Postweld heat treatment (PWHT) in the subtransus and supertransus regions did not alter the columnar grain morphology in the FZ, possibly due to the lack of enough driving force for the formation of new grains by the breaking up of the columnar grains and grain boundary movement ...

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The dependence of the photoluminescent properties of In{sub 0.48}(Al{sub {ital y}}Ga{sub 1{minus}{ital y}}){sub 0.52}P alloys (0{le}{ital y}{le}0.5) on growth temperature and substrate misorientation off GaAs(100) has been studied. Samples were grown using low-pressure metalorganic vapor phase epitaxy. By studying the dependence of ordering behavior in InGaP as a function of substrate misorientation and growth temperature simultaneously, a very large range in low-temperature photoluminescence emission energy---135 meV---has been obtained. The photoluminescence linewidth exhibits a strong, continuous dependence on the extent of atomic ordering (the emission energy) in the alloys. The results indicate that inhomogeneity in the microstructure of the material (i.e., between ordered'' domains and the disordered'' matrix) is the dominant photoluminescence broadening mechanism. This ...

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For joining type 316LN austenitic stainless steel to modified 9Cr-1Mo steel for power plant application, a trimetallic configuration using an insert piece (such as alloy 800) of intermediate thermal coefficient of expansion (CTE) has been sometimes suggested for bridging the wide gap in CTE between the two steels. Two joints are thus involved and this paper is concerned with the weld between 316LN and alloy 800. These welds were produced using three types of filler materials: austenitic stainless steels corresponding to 316,16Cr-8Ni-2Mo, and the nickel-base Inconel 182{sup 1}. The weld fusion zones and the interfaces with the base materials were characterised in detail using light and transmission electron microscopy. The 316 and Inconel 182 weld metals solidified dendritically, while the 16-8-2(16%Cr-8%Ni-2%Mo) weld metal showed a predominantly cellular substructure. The Inconel weld metal contained a large number of inclusions when deposited ...

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The aim of this work is to describe the processes during plasma nitriding of Nb-containing, powder metallurgy prepared (PM) tool steel. PM steel was studied containing 2.5% C, 3.3% Si, 6.2% Cr, 2.2% Mo, 2.6% V, 2.6% Nb and 1.0% W, produced by melt atomization and hot isostatic pressing. The hardened and tempered steel was plasma nitrided at temperatures ranging from 470 to 530 deg. C. The nitriding time was 30-180 min. Optical microscopy, electron microscopy, XRD, EDS, WDS and hardness measurements were used to study the steel's properties, microstructure, phases and chemical composition. The nitriding temperature of 470 deg. C was found to be unsuitable for practical use because the layers prepared at this temperature were non-uniform. The compound layer formed by M{sub 2,3}(C,N) and M{sub 4}N was found after nitriding at temperatures of 500 and 530 deg. C for at least 60 min. The effect of niobium on the formation of this layer was studied.

International Nuclear Information System (INIS)

Superconducting Cu-rich composites containing the A-15 compounds V_3Si or V_3Ga were made by the ''Tsuei'' process (melting into ingots followed by cold working and heat treatment). Superconducting transition temperatures of the composites were measured. X-ray diffraction analyses were performed. Microstructures were studied using both the optical metallograph and the scanning electron microscope. For some composites containing V_3Ga, the critical current densities as functions of transverse magnetic field up to 60 kG, and as functions of temperature from 4.2 to 12"0K were measured. It was found that the Tsuei process does not work for the composites containing V_3Si, but works satisfactorily for V_3Ga; reasons are discussed. Relations between measured properties and various metallurgical factors such as alloy compositions, cross-section reduction ratios, and heat treatment are discussed. The mechanism for the observed superconductivity in the ...

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A series of experiments have been conducted on AISI 5140 low alloy steel using a hollow cathode discharge-assisted plasma nitriding apparatus with the aim of elucidating the role of substrate bias voltages in plasma nitriding process. For comparison, some samples were nitrided with applied substrate bias (-50 V) while other samples were nitrided at floating potential. Treatments were carried out in NH{sub 3} atmosphere of 150 Pa at temperatures ranging from 450 {sup o}C to 550 {sup o}C for 2 h, 4 h, and 6 h. The nitrided samples were characterized by optical microscopy, X-ray diffraction and micro-hardness measurement. The corrosion behaviors were evaluated using anodic polarization tests in 3.5% NaCl solution. The results showed that the microstructure and phase constituents of the nitride layers were strongly influenced by the bias voltages. It was also demonstrated that the better corrosion resistance with a thicker nitrided layer was ...

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Al{sub x}Ga{sub 1{minus}x}P layers (0 {le} x {le} 0.7), with thicknesses of {ge}1 {micro}m were grown on Si (100) wafers by metal-organic molecular beam epitaxy (MOMBE) at 450 C. Transmission electron micrographs of the single crystal films revealed that the microstructure contains stacking faults and microtwins especially near the interface as well as both threading and misfit dislocations. Hardness and elastic modulus were measured using a Nanotest 500 indenter, which can probe the film properties without influence from the substrate. The hardness H varies linearly according to (11.8 {minus} 2.3x) GPa. The absence of alloy hardening is due to the fact that there is no difference in atomic size of Al and Ga. The indentation modulus E/(1{minus}v{sup 2}) decreases monotonically from 136 GPa for GaP to 129 GPa for Al{sub 0.7}Ga{sub 0.3}P and bows only slightly (about 2%) below the straight line of linear interpolation.

International Nuclear Information System (INIS)

For an assessment of the future US spallation neutron source (SNS) target performance, radiation induced hardening and microstructural evolution were investigated as a function of ion dose for EC316LN stainless steel. Irradiation was carried out using 3.5 MeV Fe"+, 360 keV He"+, and 180 keV H"+ simultaneous ion-beams at 200 deg. C to simulate the damage, He and H production in the SNS target vessel wall. At low dose (< 1 dpa), the predominant defects were black dots whose number density saturated rapidly within a few dpa. This was followed by the evolution of interstitial loops whose number density saturated below 15 dpa. Although He-bubbles were not visible, severely scalloped loops suggested that the implanted He/H atoms existed in the form of small clusters. Comparison with reported neutron irradiation data showed that hardening and ductility loss occurred mostly in the black dot regime (< 1 dpa), but that good ductility (>20% elongation) was maintained ...

International Nuclear Information System (INIS)

The effects of key metallurgical variables on the low fluence hardening in a set of A533B model steels were evaluated over a wide range of irradiation temperatures. Above about 163 degrees C hardening increased with higher copper and nickel contents, as is typical of the pressure vessel operating regime around 290 degrees C. However, at 121 degrees C the hardening was generally lower and unaffected by copper and nickel variations. This observation of decreased hardening with lower temperature (e.g. an open-quotes invertedclose quotes temperature dependence) is tentatively attributed to a reduced contribution of copper precipitation. Tensile data for a set of commercial steels with a range of (uncontrolled) compositions also showed minimal sensitivity to copper variations at 121 degrees C. Unlike the hardness data no systematic reductions in the yield stress increases were observed between 163 and 121 degrees C. However, the ultimate tensile strength did decrease at the lower ...

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Determination of stacking fault energy (SFE) of the austenite phase of a duplex stainless steel DIN W.-Nr.: 1.4462 has been carried out using transmission electron microscopy. Furthermore, cold rolling tests and microstructural analysis have been realized in order to allow a detailed discussion of the obtained SFE-values. The results of this investigation indicate that the stacking fault energy of the austenite phase within the duplex stainless steel is lower than of one-phase austenitic stainless steels. This is justified by the chemical composition, mainly by the Cr and Ni alloying contents. Nevertheless, work hardening of the austenite during cold deformation is not as accentuated as expected by the SFE-values, because at higher deformation levels the deformation mainly occurs within the ferrite phase 7 refs., 5 figs., 2 tabs.

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Experiments of autogenous laser full penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 3.5 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance were investigated. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. Results show that high quality full penetration laser-welded joint can be obtained by optimizing the welding velocity, flow rate of shielding gas and defocusing distance. The laser-welded seam have non-equilibrium solidified microstructures consisting of {gamma}-FeCr{sub 0.29}Ni{sub 0.16}C{sub 0.06} ...

Science.gov (United States)

Experiments of autogenous laser full penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 3.5 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance were investigated. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. Results show that high quality full penetration laser-welded joint can be obtained by optimizing the welding velocity, flow rate of shielding gas and defocusing distance. The laser-welded seam have non-equilibrium solidified microstructures consisting of ?-FeCr0.29Ni0.16C0.06 austenite solid solution ...

KoreaScience (Korea)

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International Nuclear Information System (INIS)

A large matrix of simple alloys and complex commercial type steels was irradiated over a range of fluxes at 60 FC up to a fast fluence of about 3 x 10"2"2 n/m"2. Combined with data in the literature, these results show a negligible effect of flux on irradiation hardening in the range of 2 x 10"1"3 to 5 x 10"1"8 n/m"2-s. This observation lends indirect support to the proposal that the accelerated embrittlement in the High Flux Isotope Reactor surveillance steels was due to an anomalously high level of damage from gamma rays. A weak dependence of hardening on a number of elements, including copper, nickel, phosphorus, molybdenum and manganese, can be described by a simple empirical chemistry factor. Particular combinations of elements resulted in hardening differences of up to about 60% in the complex commercial type steels and up to about 100% in simple model alloys. Direct effects of microstructure appear to be minimal. ...

International Nuclear Information System (INIS)

This report summarizes work performed by Argonne National Laboratory (ANL) on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) during the six months from October 1993 to March 1994. EAC and fatigue of piping, pressure vessels, and core components in LWRs are important concerns in operating plants and as extended reactor lifetimes are envisaged. Topics that have been investigated include (a) fatigue of low-alloy steel used in piping, steam generators, and reactor pressure vessels, (b) EAC of wrought and cast austenitic stainless steels (SSs), and (c) radiation-induced segregation and irradiation-assisted stress corrosion cracking (IASCC) of Type 304 SS after accumulation of relatively high fluence. Fatigue tests have been conducted on A302-Gr B low-alloy steel to verify whether the current predictions of modest decreases of fatigue life in simulated pressurized water reactor water are valid for high-sulfur heats ...

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The National Institute of Materials Science (NIMS) has utilized the in-house alloy design program to develop a 5{sup th} generation Ni-base single crystal superalloy, TMS-196 with superior high temperature creep, thermo mechanical fatigue (TMF) and oxidation resistance by incorporating further ruthenium (Ru) and chromium (Cr) content over the compositions of 4{sup th} generation superalloys. With Ru additions in advanced superalloys to enhance phase stability, higher content of refractory elements can be accommodated to provide further strengthening; the associated oxidation resistance can be improved by the increase in Cr additions. In present article, TMS-196 has been subjected to cyclic/isothermal oxidation tests at 1100 C and 900 C, creep at conditions between 800 C{proportional_to}1100 C/137MPa{proportional_to}735MPa and TMF cycles. Preliminary studies indicate that the surface of oxidized TMS-196 can exhibit continuous alumina layer attributing good oxidation ...

International Science & Technology Center (ISTC)

Determination of Special Molybdenum Alloys Optimal Structure Using the Cybernetic Method

International Science & Technology Center (ISTC)

Development of the Corrosion Protection Technology for Special Steels and Alloys

International Nuclear Information System (INIS)

This paper presents a new methodology to create realistic 3D microstructures of polycrystals. The virtual microstructures are based on statistical data describing the morphological and crystallographic textures of a sample, obtained from an EBSD analysis. In addition, the methodology can reproduce the observed surface on top of the simulated microstructure. This feature allows finite element calculations on these virtual aggregates to be compared to experimental results of mechanical tests. Such a comparison leads to the identification of the mechanical parameters of constitutive laws, such as critical resolved shear stress and strain hardening, using an optimization algorithm. Two materials were simulated in this study: TiAl and grade 702 zirconium. The first one presents twins inside the microstructure and the second one has an anisotropic texture. Based on 2D simulations, the important parameters ...

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Nickel-based alloys are presently used as brazing filler metals for components which undergo mechanical stress in corrosive conditions, f. e. heat exchangers. When soldering chrome containing steel parts with nickel based brazing filler metals additionally containing boron and silicon a reaction of chrome and boron can occur. This evolution of chromium borides, depositing on grain boundaries, causes a lack of chrome in the steel part. A drop of the chrome content in the parts below 13 % leads to a loss of corrosion resistance. It is possible to change the microstructure of brazing joints by modification with chromium and molybdenum. Continuous brittle phases could be successfully avoided with this modification. Furthermore it could be shown that the choice of additives, the heating respectively cooling rate and the brazing temperature have important influence on the microstructure evolution and therefore on the mechanical ...

International Nuclear Information System (INIS)

... base alloys alloys beams chemical reactions elements hardness irradiation

International Nuclear Information System (INIS)

German (Dec 1973). Germany Carlen, JC Blom, U. Sandvik Steel Works,

International Nuclear Information System (INIS)

Observations concerned with the formation of isothermal #omega# in the beta-titanium alloy RMI (38-6-44) are presented as part of a more general study of the aging characteristics of the alloy.

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NO abstract prepared.

International Nuclear Information System (INIS)

A study was made into microstructure and hardening in austenitic stainless steel 0Kh18N10T irradiated with neon ions (230 MeV) and neutrons (E_n > 0.1 MeV). The experiments were accomplished using an external beam of U-400 cyclotron (Dubna) and EWA reactor (Poland). The dependences of tensile properties, hardening index, microstructure, dislocation density on damaging dose were determined. An attempt is made to reveal the correlation between an yield strength increment and defect cluster accumulation. The interpretation of variations of mechanical properties and microstructure under irradiation is given.

Science.gov (United States)

... The ultimate compressive strength was measured, and values for Young's modulus were calculated from the linear portion of the test curve. ...

KoreaScience (Korea)

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Sprayforming offers the possibility to produce a variety of preforms in a single step directly from the melt. Numerous processing parameters ensure high flexibility but require detailed knowledge concerning the microstructure of sprayformed material depending on chemical composition and processing parameters. Within the current study fundamental investigations using unalloyed and low alloy steel grades (C15, C105, 100Cr6) for sprayforming of plates and billets have been performed concerning the influence of chromium and carbon content and selected processing parameters. Sprayformed preforms revealed austenite grain sizes up to 500 {mu}m depending on the development of porosity. Different types of porosity have been detected which can be associated with incomplete densification due to high cooling rates, solidification shrinkage and entrapped nitrogen. Atomisation gas pressure and carbon content are parameters of primary importance. (Abstract ...

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International Nuclear Information System (INIS)

The importance that must be attached to the phenomenon of stress corrosion cracking of austenitic alloys is emphasized. The relation between chemical composition of various alloys and their sensitivity to cracking is shown with particular reference to the behaviour of Alloy 800. The different effects of alkaline anc chloride environments are discussed. Studies are reported of the general corrosion of Alloy 800 and other alloys in an environment representative of the primary coolant of PWR reactors; and of the behaviour of various alloys (including Alloy 800) in the conditions envisaged for their use for steam generators with superheat up to about 550 deg.C. (U.K.).

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Two aspects of the deformation behavior of magnesium sheets are the subject of this paper. First it will give a mechanical characterization of a commercial magnesium with a focus on the anisotropy and the possible microstructural causes of this behavior. The rolling process will be part of the second aspect. The aim is to show the influence of the parameters on the microstructure and texture and how this could affect the anisotropy in the rolled sheets. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

International Nuclear Information System (INIS)

In this paper, aluminium nitride synthesis is carried out by direct laser irradiation onto an aluminium target surface in a nitrogen containing atmosphere. The influence of various processing parameters on the microstructure of AlN thin films is investigated in order to improve their tribological properties. The main microstructural characteristics: nature, concentration, in depth distribution and morphology of various phases are studied versus processing parameters by TEM and GIXD. (author). 2 refs., 1 fig., 2 photos.

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Investigations show that nickel-based alloys (MAR M 247 CC, CM DS 247 L and CMSX-4) can be successfully brazened. Tensile tests of MAR M 247 CC samples brazened with foil brazing showed values comparable to those of the base material, some samples failed because of base material problems. Tests with powder mixes made up from commercial brazens and the base material CMSX-4 showed good wetting and a perfect microstructure similar to the base material. Tensile test values at RT (test temperature) and 850 degrees centigrade show pronounced scatter. Tensile tests at RT and 850 degrees centigrade are used to optimse brazing cycles for the types of brazen used (temperature, time). (orig.) [German] Die Untersuchungen haben gezeigt, dass es moeglich ist, Nickelbasislegierungen (MAR M 247 CC, CM DS 247 LC und CMSX-4) erfolgreich zu loeten. Die im Zugversuch erhaltenen Festigkeitswerte der mit folienfoermigen Lot geloeteten MAR M 247 CC Proben erreichten ...

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Alloyed steels containing retained austenite after martensitic hardening are widely applied in technical practice. Although many practical investigations have been made into the mechanical behaviour of composite microstructures with retained austenite, there is still a lack of knowledge concerning their fatigue and crack propagation behaviour. For this reason, the author investigated the effects of retained austenite concentration and stability on the transformation and deformation behaviour of hardened states of the steels X210Cr12 and 100Cr6. For this purpose, monotone tensile tests, cyclic tensile pressure tests, and supplementary crack propagation experiments were carried out. The concentrations of retained austenite were varied between 10 and 100% by volume by means of different heat treatments. [Deutsch] Legierte Staehle, die nach martensitischer Haertung noch Restaustenit enthalten, finden in der technischen Praxis verbreitete Anwendung. ...

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In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs under cyclic and ...

International Nuclear Information System (INIS)

Due to the well-establish corrosion problems of Alloy 600 as a steam-generator material and the subsequent focus on thermally treated (TT) Alloy 690 and Alloy 800 as alternative materials, a systematic analysis of the corrosion behavior of these two latter alloys is warranted. Corrosion test results for Alloys 690 TT and 800 were collected and organized in the form of corrosion mode diagrams. Selected data for mill annealed (MA) Alloy 600 were also included for reference. The corrosion mode diagrams correlate the modes of corrosion degradation observed in tests as functions of the environment pH and electrochemical potential (ECP). The diagrams confirm that Alloys 690TT shows some susceptibility in caustic environments, and Alloy 800 shows susceptibility in both caustic and highly acidic environments. (authors). 6 figs., ...

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Water repellency en the microstructure super-hydrophobic cured surface is important for research and industrial purposes. This microstructure film can be cured on polyethylene terephthalate PET surface by electron beam (EB) at different irradiation doses 10-100 kGy. The microstructure formulation composed from hydrophobic acrylate oligomer (EB 244) and monomer (SR 440). The irradiation induced cross linking of the prepared microstructure was proved by FTIR spectroscopy and the adhesion force by abrasion test. Some factors affecting the adhesion force of the prepared microstructure film such as oligomer/monomer composition ratio and the thickness of the microstructure cured film were studied. The contact angles (8) were measured on cured surfaces before and after adding the super hydrophobic nanoparticles (Zonyl 9361). The super-hydrophobic cured surface showed ...

International Nuclear Information System (INIS)

Consideration is given to the process of the formation of a titanium sponge alloyed with niobium or tantalum, in the joint metallic reduction of titanium, niobium and tantanum chlorides. A percentage composition of the phases observed and the structure of the alloyed sponge have been studied. It is shown that after one remelting operation of the alloyed sponge the alloys of titanium with niobium and tantalum have a uniform component distribution. At the stage of chloride reduction there appear solid solutions based on titanium and an alloying component. The stage of vacuum separation of the reaction mass is associated with a mutual dissolution of the primary phases and the formation of the solid solutions of the alloyed titanium sponge, which, by their composition, are close to the desired alloy composition. The principal features of the ...

International Nuclear Information System (INIS)

The following methods of quartz ceramics alloying were considered: alloying of initial quartz glass; introduction of alloying additive into water slip of quartz glass; porous materials impregnation with salt aqueous solutions and subsequent salt thermal decomposition with formation of stable oxides in pores of ceramics. Oxygen free compounds BN, SiB_4, SiC, Si_3N_4, REM oxides and transition metal oxides were used as alloying additives. Main properties of the materials and compositions obtained are presented.

Energy Technology Data Exchange (ETDEWEB)

The processing characteristics, tensile properties, and oxidation response of two Nb-Ti-Al-Cr alloys were investigated. One creep tests at 650{degrees}C and 172 MPa was conducted on the base alloy which contained 40Nb-40-Ti-10Al-10Cr. A second alloy was modified with 0.11 at. % carbon and 0.07 at. % yttrium. Alloys were arc melted in a chamber backfilled with argon, drop cast into a water-cooled copper mold, and cold rolled to obtain a 0.8-mm sheet. The sheet was annealed at 1100{degrees}C for 0.5 h. Longitudinal tensile specimens and oxidation specimens were obtained for both the base alloy and the modified alloy. Tensile properties were obtained for the base alloy at room temperature, 400, 600, 700, 800, 900, and 1000{degrees}C, and for the modified alloy at room temperature, 400, 600, 700, and 800{degrees}C. Oxidation ...

International Nuclear Information System (INIS)

Investigated are the characteristics of high-temperature plastic deformation the velocity sensitivity of flow stresses, deformation curves, flow stresses, deformation before rupture - as well as the structure of beryllium alloys containing nickel (0.5-4 %), yttrium (0.5-2 %) and aluminium (38 %). The alloys containing nickel (2%) and yttrium (0.5 %) are superplastic, however, deformation before fracture of the alloys is lower than that of the unalloyed beryllium. The singularities of high-temperature plastic flow of the alloys and the causes of deterioration of their plasticity are determined.

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Three model boilers, manufactured to simulate full-size tube sheet crevices, were tested with various secondary side environments. The first was faulted with organics representative of the decomposition of humic acid. The second was faulted with sodium carbonate and sodium hydroxide, while the third was faulted with sodium sulfate and sodium hydroxide. Each model contained seven tubes, which included Alloy 600 in the mill-annealed (MA) and thermally-treated (TT) conditions and Alloy 690 in the thermally-treated condition. Two models contained Alloy 800 tubes in the mill-annealed condition and one had Alloy 800 in the mill-annealed/cold-worked/glass-bead-peened condition. Two different sizes of tubesheet crevices were used in all model boilers. In the organics-faulted boiler, tubes of Alloy 600MA, Alloy 690TT and Alloy 800MA experienced no ...

Energy Technology Data Exchange (ETDEWEB)

In order to design the microstructure of ceramics with desired dielectric property, an estimation method of dielectric constant of ceramics taking into account the characteristics of microstructure of the ceramics is proposed. In the estimation model, the microstructure of ceramics is represented by the assembly of unit cells comprising of grain, pore and grain boundary. The sizes of grain and pore and the thickness of grain boundary in each unit cell were determined exactly according to their size and thickness distributions in a real ceramic. The dielectric constant of the assembly can be calculated on the basis of equivalent circuit theory. The estimated values of dielectric constant of ceramic BaTiO{sub 3} using the proposed estimation method agree well with experimental ones. The dependence of characteristics of microstructure on the dielectric constant was clarified by the estimation of dielectric ...

International Nuclear Information System (INIS)

Thermal analysis testing revealed slight weight changes, which were a function of gamma irradiation, in a highly reduced Defense Waste Processing Facility (DWPF) simulated waste glass. Transmission electron microscopy (TEM) was performed on this glass to determine if the weight change corresponded to microstructural variations. TEM analyses showed that no microstructural changes were attributable to gamma irradiation. Exposure of the samples to the electron beam in the TEM did cause changes in the glass microstructures in some cases. These changes were likely due to localized heating of the glass due to interactions with the transmitted electrons.

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Resistance of ALLOY 800 as a PWR/SG tubings to IGC/IGSCC and Ni, Co release into high temperature water was evaluated as compared with ALLOYs 600 and 690. The study to improve the resistance to IGSCC and general corrosion was also made. From the results, ALLOY 800 was evaluated to be the most reliable among the high Ni alloys tested. In addition, the alloy would obtain further reliability in IGSCC and general corrosion resistance by the combined addition of Ti and Nb, and the prior oxidation treatments, respectively. (author).

Science.gov (United States)

Pore Fraction in Yttrium-Barium-Copper-Oxide and. Other Polycrystalline. Materials ...... Properties of Yttrium Ceramic. Sov. J. LowTemp.Phys. 14:395-402 . ...

International Nuclear Information System (INIS)

Zirconia-toughened sialon composites have been fabricated using conventional hot-pressing techniques. The fracture toughness and microstructure were determined for CeO_2- and Y_2O_3-stabilized ZrO_2 additives and also as a function of volume percent ZrO_2. The Yttria system showed a linear increase in fracture toughness with increasing volume fraction zirconia content while the ceria-stabilized system exhibited a peak in fracture toughness at 20 vol% ZrO_2 content. The fracture toughness at 800 C was measured and correlated with the microstructure. High-temperature stability was determined and it was found that the deleterious nitride phases of zirconium could be precluded from the microstructure.

KoreaScience (Korea)

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Science.gov (United States)

... Accession Number : ADD151811. Title : Ultra High Strength Beta Titanium Alloy for Fasteners. Descriptive Note : Journal article,. ...

Science.gov (United States)

... Accession Number : ADD109273. Title : THERMAL STABILITY OF ALPHA-BETA TITANIUM ALLOY Ti-5Al-2Cr-1Fe,. Corporate Author : ...

Science.gov (United States)

... by the boron doping in most of the alloys except for Al66Mn9Zr25 + 50 ppm B alloy; permanent deformation at ultimate compressive strength is not ...

International Nuclear Information System (INIS)

The nickel-rich superalloys Alloy 600 and Alloy 800 have been corroded in mildly alkaline deuterated aqueous conditions typical of secondary coolant circuits in a nuclear power station. The oxide films and substrates of these alloys have been analysed by imaging SIMS depth profiling, which makes it possible to describe elemental distribution in all three dimensions. The measurement of the distribution of the secondary ions NiO"-, FeO"- and CrO"- appears useful for detailing the behaviour of nickel, iron and chromium within oxidized phases. The measurement of D"- distribution outlines the extent of oxide hydration. For Alloy 800, evidence of sodium migration into the grain boundaries of the alloy substrate is found. For Alloy 600, no grain boundary sodium ingress can be identified under comparable corrosion conditions. (author).

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Four low activation alloy classes, two austenitic and two ferritic, have been incorporated into the MOTA-1B experiment in the FFTF reactor to provide an early assessment of the suitability of such alloys for reactor service.

International Nuclear Information System (INIS)

The effect of various hydrogen concentrations on the crystal lattice period and the hardness of titanium alloy was examined, the alloy containing about 16 at.% Mo (27.5 wt. % Mo) and having #beta# structure. The peculiar features of the mechanism of plastic deformation of the alloy were studied after adding hydrogen to it. A dependence of the crystal lattice period on the concentration of hydrogen was obtained for TixMoxH_2 alloy. It has been established that the hardness of the Ti-Mo alloy does not change when hydrogen is added to it. The presence of hydrogen introduces changes into the mechanism of deformation of #beta#-titanium alloy. The configuration of the inverse pole figures after rolling proves that the transverse slip process in an alloy with hydrogen is hampered, and that the coplanar slip process is developing in it.

Science.gov (United States)

... CLOSURE DURING HOT WORKING OF AN ALPHA/BETA TITANIUM ALLOY (PREPRINT) ... HOT WORKING OF AN ALPHA/BETA TITANIUM ALLOY ...

Science.gov (United States)

... Accession Number : ADD336001. Title : Development of a FeCoNb Alloy to be used in Eddy Current Probes for Testing Ferromagnetic Tubes,. ...

Science.gov (United States)

... Title : DUCTILITY RATIO OF AGED BETA TITANIUM ALLOY. Corporate Author : NEW YORK UNIV NY SCHOOL OF ENGINEERING AND SCIENCE. ...

International Nuclear Information System (INIS)

Stemming from their unique combination of elevated strength, low density, and good overall corrosion resistance, beta titanium alloys have become attractive candidate materials for critical, high-stress, components in corrosive services. An overview of the comparative corrosion resistance of beta alloys to conventional alpha and alpha/beta titanium alloys in common industrial and aerospace service environments generally reveals attractive behavior depending on the environment and alloy composition and, in some cases, alloy condition. Expanded performance windows are especially noted for the molybdenum-rich beta alloys, particularly in regard to resisting reducing acids, stress corrosion, and high temperature localized chloride attack, along with hydrogen and oxidation resistance. Where applicable, implications of this enhanced corrosion performance on current ...

Energy Technology Data Exchange (ETDEWEB)

Whereas supersaturated aluminum alloys demonstrate enhanced passivity, conventional aluminum alloys spontaneously pit in air-saturated chloride solutions. We have concentrated on three areas: evaluation and characterization of Al-W alloys, which exhibit the best corrosion performance of any alloy system studied to date; characterization of the passive-film structure of Al-Mo alloys; and production and characterization of Al-W and Al-Ta powders, which will be used for compaction into bulk material. Surface analysis of the Al-W passive films formed during polarization show surprising little oxidized solute compared to other alloys. These results indicate that the barrier layer formation and electrostatic repulsion mechanisms used to explain the passivity of other alloys are not involved here. Instead the W may act to stabilize the passive film ...

Energy Technology Data Exchange (ETDEWEB)

To clarify the acidic and alkaline Intergranular Stress Corrosion Cracking (IGSCC) mechanism of thermally treated alloy 690 (alloy 690 TT) and shot peened alloy 800 (alloy 800 SP), C-ring tests were conducted in deaerated HCl solutions and in deaerated NaOH solutions at 350degC, compared with the acidic and the alkaline IGSCC susceptibilities of mill-annealed alloy 600 (alloy 600 MA), full-sensitized one (alloy 600 FS) and thermally treated one (alloy 600 TT). Grain boundary characteristics, such as chromium depleted zone and chromium carbide precipitation, were examined using modified Huey test and Transmission Electron Microscopy. Potential-pH diagram for Ni, Cr, Fe-H{sub 2}O system at 350degC was constructed and the solubilities of NiO, Cr{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} were also calculated to evaluate the ...

Energy Technology Data Exchange (ETDEWEB)

The macroscopic behavior of magnetostrictive materials results from domain evolutions occurring at a microscopic scale. The author shows how to compute magnetization and magnetostriction curves by appraising the behavior of the underlying microstructures. The method hinges on an averaging device (Young measures), which allows one to pass from the microscopic to the macroscopic scale. He takes into account the kinematical constraints on the accommodation of elastic effects, and he highlights the role of material symmetry in the selection of energetically optimal microstructures.

KoreaScience (Korea)

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International Nuclear Information System (INIS)

The investigations carried out on Alloy 800 in aqueous high-temperature environments in France as well as in other countries are reviewed. These studies are mainly concerned with nuclear industry where Alloy 800 can be used as structural material for steam generators of PWR, breeders or HTR. As results referred to in the literature on cracking in caustic environmens do not always agree, a discussion is presented on the matter. The behaviour of Alloy 800 in superheated steam is examined. (Auth.).

International Nuclear Information System (INIS)

(Nov 1973). United States Greenfield, MA Pierce, CM Chicago, IL.

KoreaScience (Korea)

Full Text Available

International Science & Technology Center (ISTC)

Investigation of Destruction Mechanisms in Reactor Steels and Alloys under Cycling Deformation

Science.gov (United States)

Not Available

International Nuclear Information System (INIS)

General corrosion behavior of ALLOY 800 in high temperature water was studied in relation to its surface film structure. The surface film formed in water was found to decrease the corrosion rate of ALLOY 800. This film is composed of Ni ferrite, and can be obtained by oxidation in air or steam. Based on these results, air or steam oxidation treatment to inhibit Ni and Co release of ALLOY 800 into high temperature water is proposed. (author).

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

This paper describes a process for the direct production of a superconductive niobium-titanium alloy during reduction of niobium pentoxide. It comprises: mixing at least one of titanium metal powder and titanium dioxide powder with niobium pentoxide powder and aluminum powder; heating the resulting mixture to form a niobium-titanium alloy and a slag consisting essentially of aluminum oxide; and separating the alloy and the slag.

Energy Technology Data Exchange (ETDEWEB)

Simulated atmospheric corrosion studies were performed to determine the corrosion protection provided by galvanized zinc coatings on depleted uranium, U-0.75 Ti alloy, and U-6 Nb alloys. The accelerated ASTM tests consisted of exposing the galvanized samples to aqueous and aqueous chloride environments. The test results showed that anodic protection was provided by the electronegative zinc coatings on uranium and uranium alloys. Treating zinc with chromate conversion coatings also provided more protection.

Energy Technology Data Exchange (ETDEWEB)

Spray depositing allows the production of steels having a structure which is free of any macro-segregation, homogeneous and equiaxed. Nevertheless the spray deposition of steels shows some effects that have to be regarded as disadvantages. A porous region at the billet border and a rather coarse-grained microstructure can be noticed. As a result, in the presented work the influence of a subsequent hot rolling and a following heat treatment on microstructure and mechanical properties has been investigated. For this purpose the bearing steel SAE 52100 has been used as master material. The initial microstructure has been transformed to a homogeneous equiaxed fine-grained pearlitic microstructure without any remaining porosity. To get use of the characteristic properties of this high-strength steel an isothermal bainitic hardening has been carried out. Information about the mechanical properties of this ...

International Nuclear Information System (INIS)

Buried silicon carbide (SiC) microstructures with lateral dimensions in the #mu#m range were formed by high-dose projection of 1.5 MeV C"2"+ ions in Si(100) at different doses and temperatures and subsequent annealing for 10 h at 1250 deg. C. Sections of individual SiC microstructures were prepared for cross-sectional transmission electron microscopy (TEM) analysis using a focused ion beam (FIB). Besides the possibility to select an individual microstructure, the FIB technique has the advantage of producing specimen foils of uniform thickness. Therefore, it was possible to map the carbon concentration of microstructures by energy filtered TEM (EFTEM) using the C_K absorption edge without the need of any sample thickness correction. Local overstoichiometric (>50%) carbon concentrations are shown to be correlated to the formation of an amorphous phase in the SiC and to significant swelling visible at ...

International Nuclear Information System (INIS)

A new high strength titanium alloy has been developed primarily intended for fastener applications. While Ti-6Al-4V is used extensively as a fastener alloy in the aerospace industry, its shear strength allowable is limited to 655 MPa (95 ksi). For higher shear strength requirements, various steels or nickel-based alloys are used (up to 860 MPa (125 ksi)), but with the attendant density penalty. This new alloy is intended to provide the 860 MPa shear strength at roughly a 40% weight savings. After screening various alloy systems, the optimum chemistry has been selected as follows: Ti-6.0V-6.2Mo-5.7Fe-3Al. In light of its 125 ksi shear strength goal, the alloy has been designated TIMETAL reg-sign 125.

Energy Technology Data Exchange (ETDEWEB)

In a work studying the corrosion and tarnishing properties of a variety of copper alloys, the alloy Cu-A110-Sn5 was found to show an excellent corrosion resistance in neutral solutions, where copper and most conventional Cu alloys are covered by thick nonprotective surface layers. The passive films formed on this alloy were characterized with electrochemical and photoelectrochemical methods. The pH dependence of the passivation and of the photocurrent behavior of the Cu-A110-Sn5 alloy clearly indicates that the passivity of this alloy in neutral solutions is due to a formation of passive film enriched with aluminum oxide. At corrosion potential a strong increase in the corrosion resistance with time is due to a gradual enrichment of the surface with aluminum oxide. This can be seen in the photocurrent spectra which change from cooper-type to aluminum-type with ...

Energy Technology Data Exchange (ETDEWEB)

It is hypothesized that the good performance of Alloy 800 in steam generator service is due to its relative immunity to two distinct mechanisms of stress corrosion cracking; the argument also applies to intergranular corrosion. One mechanism operates in the high-nickel region (Alloy 600 and nearby model alloys) and is due to internal intergranular oxidation. The other operates in the low-nickel (stainless steel) region and is due to de-alloying of Fe and/or Cr. This latter mechanism may, under special conditions, operate in high-Ni, high-Cr alloys such as 690. Some essential features of the de-alloying mechanism are demonstrated using strong caustic solutions, and the prospect of extending this approach to dilute high-temperature environments is discussed. (author)

British Library Electronic Table of Contents (United Kingdom)

Statement of problem. The popularity of base metal alloys has considerably increased in recent years because of their superior mechanical properties as well as the high cost of noble alloys. However, there is disagreement about their effect on the opaque porcelain color and the color differences among base metal alloys. Purpose. The purpose of this in vitro study was to determine and compare the influence of various commercially available base metal alloys (excluding titanium-based systems) on the resulting color of opaque porcelain with the use of a colorimetric device. Material and methods. Fourteen different types of Ni-Cr and 3 different types of Co-Cr porcelain bonding alloys were selected with a Au-Pd alloy (V-Delta SF) as the control group for colorimetric measurements and determina...

International Nuclear Information System (INIS)

The paramagnetic susceptibility of single crystals of dysprosium-yttirum alloys is measured in the basal plane and along the hexagonal axis. It is shown that the susceptibility of the alloys obeys the Curie-Weiss law, the effective magnetic moments allong the different directions being the same and the paramagnetic Curie temperatures being different. The difference between the paramagnetic Curie temperatures in the basal plane and along the hexagonal axis is independent of the dysprosium concentration in the alloy. As a comparison with the theoretical models of magnetic anisotropy shows, this is an indication that the magnetic anisotropy of dysprosium - yttrium alloys is of a single-ion nature.

Energy Technology Data Exchange (ETDEWEB)

Friction stir welding of dissimilar formed Mg alloys(AZ31/AZ91) was successfully carried out at the limited welding conditions. In a sound joint, SZ was mainly consisted of AZ31 Mg alloy which was located the retreating side. Dynamic recrystallization and grain growth occurred and {beta} intermetallic compounds of AZ 91 Mg alloy was not observed in SZ. BM had a higher hardness than that of the weld zone. The fracture location was not weld zone but BM of the AZ91 Mg alloy in tensile test. (orig.)

International Nuclear Information System (INIS)

The creep crack growth properties of two versions of Alloy 800 have been compared at 500 and 600"0C in the Grade II condition in tests up to 10"4 hours duration. The two alloys were a low carbon alloy containing (wt.%) 0.024 C, 0.5 Ti, 0.3 Al (Alloy B) and a higher carbon alloy containing (wt.%) 0.038 C, 0.2-0.3 Ti, 0.2-3.0 Al (Alloy J). At 600"0C, Alloy B attained maximum age hardening in 10"2 hours, whereas J did not harden significantly in time up to 10"4 hours. Both alloys age hardened at 550"0C with Alloy J hardening more rapidly than B. The creep displacements and displacement rates in small compact tension specimens at 600"0C were smaller than Alloy B than in Alloy J. However, failure times were shorter in Alloy B because of lower ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this work was to investigate the role of chromium on hydrogen embrittlement of Ni-Cr-Fe alloys and thus to develop a better understanding of the low-temperature stress corrosion cracking (SCC) phenomenon. The effect of chromium on hydrogen embrittlement was examined using tensile tests followed by material evaluation via scanning electron microscopy (SEM) and light optical microscopy. Four alloys were prepared with chromium contents ranging from 6 to 35 wt pct. In the uncharged condition, ductility, as measured by the percent elongation or reduction in area, increased as the alloy chromium content increased. Hydrogen appeared to have only minor effects on the mechanical properties of the low-chromium alloys. The addition of hydrogen had a marked effect on the ductility of the higher-chromium alloys. In the 26 pct chromium alloy, the elongation to ...

Science.gov (United States)

The purpose of this communication is to determine whether the solubility enhancements for cold-worked Pd-Ni alloys increase or decrease with atom fraction of Ni. Substitutional Ni atoms contract and Pd lattice, in contrast to the lattice expansion resulting from substitutional Ag in Pd. The Pd-Ni alloy system forms a continuous series of fcc solid solution alloys over the whole composition range. The solubility enhancements will also be determined for a series of homogeneous, ternary Pd[sub 1[minus]x]Ni[sub 1/2x]Ag[sub 1/2x] alloys for x in the range from 0 to 0.2. For this series of ternary alloys the fcc lattice parameters do not change significantly from that of pure Pd. The alloys used in this research were purchased from Tanaka Kikinzoku Kogyo K.K. The detailed experimental procedure has been described previously. The alloys were all ...