Suitable Alloy Research Articles

Microstructure and bonding behavior of a new Hf-bearing interlayer alloy for single crystal nickel-base superalloy

Single crystal nickel-base superalloys have been widely used in aero-engine blades, but a limited factor is that this kind of alloy is very sensitive to hot cracking during fusion welding due to high content of {gamma}{prime}-former such as Al, Ti. Transient liquid-phase(TLP) bonding has been developed to join the superalloys susceptible to hot cracking. It is very important to design a suitable interlayer alloy which does not contain any deleterious phases and has a melting point lower than that of the base metal. At present, the interlayer alloys which generally used for superalloys are of the Ni-Cr-Si-B system. However, addition of B and Si should be avoided because these elements are harmful impurity elements in single crystal superalloys. Hf is a potential melting point depressant in the interlayer alloys which has not been evaluated up to date. The goal of this investigation is to characterize the microstructure of a Hf-bearing interlayer alloy and determine the effect of Hf on the solidification of bonding layer during TLP processes for single crystal superalloys.

高周波イオンプレーティングによる金・アルミニウム合金薄膜の形成

Purple Au-Al alloy films were deposited on glass substrates using a radio frequency ion plating method. Au-Al alloys were used as source materials. The effects on the film of the source alloy composition and the evaporation time were studied. The color tones of the deposited films were measured using spectral reflectance and their crystal structures were studied by X-ray diffraction. As a result, a composition of Au 80%-Al 20% was chosed as the most suitable source alloy. The color tone of a film deposited from a single evaporation source changed from white to purple as the evaporation time increased. The intensity of the X-ray diffraction pattern of the AuAl2 sharpened as the color tone of the film became more purpler. The purple color of the film became brighter after 1hour of heat annealing at 550°C in an atmosphere of Ar (8×103Pa).

A study on the hydrogenation properties of the MmNi4.5Al0.5Zrx (x = 0−0.2) alloys

Abstract Hydrogenation properties of the MmNi 4.5 Al 0.5 Zr x ( x = 0−0.2) alloys are investigated by means of PC-isotherm measurements, X-ray diffractometry, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). As the Zr content increases, the first hydriding reaction is completed in a shorter time, but the plateau pressure is sloped and decreases. At a composition of x = 0.05, a maximum hydrogen storage capacity is obtained with a enhanced activation property. Upon pressure cycling of the MmNi 4.5 Al 0.5 Zr 0.5 alloy, the hydrogen storage capacity is decreased by only 8% after 4300 cycles. From the X-ray diffraction, SEM and EDX tests, new second phases are observed at high Zr content above x = 0.1. The major second phase is confirmed to be the ZrNi 3 phase. It is considered that the improved activation properties of the MmNi 4.5 Al 0.5 Zr x alloys are caused by the strong catalytic effect of ZrNi 3 on the dissociative chemisorption of hydrogen molecule. Among the investigated alloy systems, it is suggested that the most suitable alloy is the MmNi 4.5 Al 0.5 Zr 0.05 as a new hydrogen storage material due to its the large hydrogen storage capacity, the improved activation behavior and the strong resistance to the degradation in the subsequent cyclic operation.

The development of Spangold

The underlying mechanisms of martensitic phase transformations in gold alloys have attracted a great deal of study. Whereas their technological exploitation in shape-memory devices has found only limited application, theSpangold concept introduces a novel application — that of using the transformation to decorate gold ornaments. This article examines the attributes of suitable alloys and the development of a prototype alloy for use in jewellery.

ろう付け性を有するアルミニウム合金鋳物製フランジの開発

In the development of flange made by an aluminum alloy casting for an air intake manifold (AIM) of a car, Al-Zn-Mg, Al-Mn-Mg, Al-Mg and Al-Mg-Si alloys were investigated on their casting properties, strength and brazability with A6063 alloy extrusion tubes. The alloy for the flange was required to have a solidus temperature higher than that of A4045 alloy and to have Mg content less than 0.6 mass%. Consequently, 712.0 alloy, which was inferior to Al-6Si alloy in casting properties but strong enough after the exposure to the brazing temperature, was chosen as the most suitable alloy for the flange. The casting design without defects was also studied using this alloy. Based on the fact that shrinkages were located in the part where G/√R_??_0.5 (G: the gradient of temperature, R: the cooling rate), the production of the casting flange without defects has been achieved by a high and long neck in the riser of the sand mold.

Irradiation-induced softening of Ni3P and (Ni,Fe,Cr)3P alloys

Production of amorphous alloys by solid state reactions (SSR) has attracted much interest during the last few years. One of the methods to induce such a reaction is the irradiation of suitable crystalline alloys by fast particles. Examination of this kind of SSR in M[sub 3]P type of brazing alloys (M: Metal) is attractive because of the following reason: In brazed joints of candidate structural materials like 316L stainless steel for applications in fusion reactors, crystalline intermetallic phases have been detected which are unstable relative to the amorphous state when irradiated at moderate temperatures with fast particles. It is expected that the transition to the amorphous state is accompanied by changes of the mechanical properties, which are of fundamental interest in this context. Until now, only a few studies on the evolution of mechanical properties during amorphization have been performed. Measurements of microhardness of the crystalline and the corresponding amorphous phase do not exist to the authors knowledge. In this communication, the authors present results on changes of microhardness, due to amorphization by fast ions. The measurements have been performed on a model alloy Ni[sub 3]P and on the brazed joint of stainless steel 316L, containing M[sub 3]P (M: Ni,more » Fe, Cr) as one of the phases. Though microhardness is not a fundamental property of materials, it is a manifestation of several related properties, such as yield stress, ductility, work-hardening, elastic modulus and residual stress states. It represents a resistance for indentation and is, therefore, appropriate for comparative purposes.« less

Ｐｄ‐Ｃｕ系ろうによるチタン合金Ｔｉ‐６Ａｌ‐４Ｖのろう付継手特性

The purpose of this study is to develop palladium braze alloys for titanium alloy Ti-6Al-4V with jointing and cost characteristics superior to nickel-based or gold-based filler metals.This paper summarized the metallurgical and mechanical properties of titanium alloy Ti-6Al-4V joints with three types o f developed Pd-Cu system braze alloys, 30Pd-40Au-30Cu, 30Pd-60Cu-10Co, 30Pd-60Cu-10Ni, and the commercial nickle-based filler metal Ni-Cr-W-Fe-B-Si.The results obtained were as follows:(1) The intermetallic compounds Ti2Cu and TiCu were formed at the brazed joints with palladium braze alloys, and the intermetallic compound Ti2Ni was formed at the brazed joint with Ni-Cr-W-Fe-B-Si.(2) The joints brazed with the 30Pd-60Cu-10Ni filler metal had the highest tensile strength at room temperature at the joint clearance 0.10mm.(3) The 30Pd-60Cu-10Ni filler metal showed the highest tensile strength at 473K and 673K.(4) The most suitable palladium braze alloy tested for titanium alloy Ti-6Al-4V is the 30Pd-60Cu-10Ni braze alloy.

Effects of nickel and chromium on corrosion rate of linepipe steel

The effects of alloying elements, such as nickel and chromium, on the corrosion rate of linepipe steels have been investigated using electrochemical techniques; suitable alloy designs are proposed for both weld metal and base metal. Anodic-polarization measurements revealed that the addition of nickel to the weld metal depolarizes the anodic-polarization curves while the addition of chromium to the weld metal polarizes the cathodic-polarization curves. The differences in corrosion-current densities between the base metal and the weld metal obtained by the Stern-Geary method were independent of nickel content; on the other hand, the corrosion-current density became smaller by the addition of chromium to the weld metal. The role of nickel and chromium on the corrosion rate was mechanistically considered from the viewpoint of corrosion-film characteristics using the a.c. impedance technique. It was elucidated that addition of chromium results in a very tight corrosion film, with higher corrosion resistance arising from formation of Cr 2O 3 on the surface of the weld metal.

Tailoring of Schottky barrier heights in Si and GaAs using metal alloys for infrared detectors

The tailoring of Schottky barrier heights in semiconductors for IR detectors is still a difficult task. Various approaches to modify barrier heights have been reported in the literature. A comparatively easier technique for tailoring barrier heights in Si and GaAs by adjusting the alloy composition of suitable metal alloys is proposed in this paper. The experimental verification of this technique, using Pd-Al alloy Schottky contacts on p-type Si, is also reported.

Mass spectra of alloy liquid metal ion sources (abstract)

Liquid metal ion sources are widely used in focused ion beam systems with applications such as maskless ion implantation and microfabrication. For these applications a variety of technologically important ions are required. Alloys with a eutectic composition as source feed materials are generally used and the desired ions are selected by means of a mass separating system. This paper presents the results of mass spectrometric investigations on Pd-Ge, Cu-Ge, Au-Si-Be, Au-Si-Sb, Au-Ge-Sb, and Pt-Sb-P-Au-Si alloys using tungsten as needle material. The suitable atomic alloy composition was deduced from the corresponding phase diagrams and the temperature range of melting of the employed alloys was determined by differential thermal analysis. Relative intensities of the main ion species in dependence on the total source current were investigated.

Tailoring of Schottky barrier heights in Si and GaAs using metal alloys

The tailoring of Schottky barrier heights in semiconductors is still a difficult task. Various approaches to modify barrier heights have been reported in the literature. A comparatively easier technique to tailor barrier heights in silicon and GaAs by adjusting the alloy composition of suitable metal alloys is proposed in this paper

Codepositing elements by halide-activated pack cementation

The codeposition of two or more elements in a halide-activated cementation pack is inherently difficult because of large differences in the thermodynamic stabilities for their volatile halides. However, through a computer-assisted analysis of the pack equilibria, combinations of suitable master alloys and activator salts can be identified. The codeposition of chromium plus aluminum or chromium plus silicon by pack cementation has yielded diffusion coatings with excellent resistance to high-temperature oxidation and corrosion fora wide range of alloy substrates.

DESIGN OF ACTUATING ELEMENTS MADE OF SHAPE MEMORY ALLOYS

Actuating elements made of shape memory alloys can be used in many sectors of industry. Examples include aerospace, auto manufacture, household appliances, medical equipment, heating, ventilation and air conditioning, fire protection, electrical equipment and model construction. Requirements to be taken into account for the selection of the suitable alloy, the component design and the effect stability for a particular application are explained.

Effect of additive elements on magnetic properties and irreversible loss of hot-worked Nd-Fe-Co-B magnets

There has been limited work on the effects of alloying elements on the properties of hot-worked anisotropic magnets. The coercivity mechanisms for sintered and rapidly solidified Nd-Fe-B magnets are different, and additives can have different effects on magnetic properties. The present study was conducted to clarify the effects of various alloying elements on the properties of hot-worked magnets. Ribbons of composition (Nd13.6−xRx)(Fe77.6−yTyCo2.8)B6.0 (R=Ce and Dy; T=Al, V, Cu, Ga, Zr, Nb, Mo, and Sn; x=0, 1, and 2; y=0, 0.5, and 1.0) were prepared by melt spinning. Anisotropic magnets were made at 1073 K with 55.6% reduction in height by die upsetting. Room-temperature magnetic properties and irreversible losses after exposure at 323–473 K were determined. The results showed that small amounts of Al, V, Cu, and Ga enhanced the remanence of the magnets, while Dy, Al, Ga, Zr, Nb, and Mo improved the coercivity. Dy, Ga, and Mo additions were effective in increasing the heat resistance temperature (HRT), defined as the temperature where the irreversible loss is 3%. HRT is dependent on initial intrinsic coercivity and the squareness ratio (Hk/iHc) of the demagnetization curve. An equation relating these parameters is given. An HRT of 453 K was obtained with a suitable alloy composition.

Manufacturing Process of Turbine Disk Materials by Combination of Eccentric Rotating Casting and Forging Processes

A new process comprising a new grain refining cast process (KM process) and a new forging process (SIRD process) has been developed to make a low cost and high performance turbine disk. It was found that the SIRD process can be a breakthrough technology with better forging efficiency than the conventional isothermal forging process. After experiments over various superalloys, IN792 Mod5A was found to be the most suitable alloy with performance almost equal to those of the conventional powder forged materials

The prevalence of sensitivity to constituents of dental alloys

Ninety-five participants were epicutaneous patch tested in order to determine the prevalence of sensitivity to components of dental alloys. Seventeen individuals (17.9%) developed allergic reactions, which were caused by mercury (10.5%), copper (2.1%), nickel, cobalt, tin, gold and zinc (1.1%). Eight of 17 allergic responders had a history of dermatitis from metal contact. The results show that there is a need for careful immunological considerations during the selection of suitable alloys, particularly in the case of patients with lesions suspected of being caused by dental alloys.

On the Evaluation Methods of Ni-Base Corrosion Resistant Alloy for Sour-Gas Exploration and Production

Abstract The effect of Cr, Ni, and Mo contents of Ni-base alloy on the corrosion behavior in H2S—CO2—Cl− environment with elemental sulfur at elevated temperature was investigated. The environmental with elemental sulfur was more corrosive than that without elemental sulfur. The stress corrosion cracking (SSC) resistance of Ni-base alloys increases with increasing Ni and especially Mo contents. The main effect of the elemental sulfur is considered that the generation of H2S due to the cathodic reaction of elemental sulfur at a location underneath sulfur deposition, which is related to the viscosity of elemental sulfur. Recommendable chemical composition of Ni-base alloys in H2S—CO2—Cl−-S environment was proposed from the view points of phase stability, stress corrosion cracking, and hydrogen embrittlement (HE). Suitable high-Ni alloys had more than 12%Mo and 15%Cr and the phase stability parameter (Md) value below 0.911.

Rapidly solidified Al-Ti alloys via advanced melt spinning

Rapidly solidified Al-Ti based binary and ternary alloys containing 3 to 12 wt.% titanium and additions of cerium or vanadium have been produced by melt spinning continuous ribbons, pulverization into powders and consolidation by hot-extrusion into round bars. The mechanical property data show that significantly improved elevated-temperature strengths can be obtained by suitable alloy design and processing. The rapidly solidified Al-Ti base alloys have improved general corrosion and pitting corrosion resistance in comparison to ingot metallurgy Al 7075-T73 alloys and higher resistance to pitting corrosion than rapidly solidified Al-8Fe-2Mo.

Investigation of helium and hydrogen deposition in an accelerator based neutron source

One of the major obstacles to be surmounted in the design of a controlled thermonuclear reactor (CTR) is the requirement of structural materials which can tolerate the intense radiation environment surrounding a fusion reactor core. The long lead time required for the development of suitable new alloys underscores the need for an intense source of energetic neutrons which can “simulate” the radiation environment associated with a fusion plasma. Among the various accelerator based neutron sources which have been proposed for such a simulation, the spallation neutron source (SNS) is considered to be very promising [1,2]. However, before the technical feasibility of SNS as a tool for simulation of radiation damage characteristics of a CTR can be established we have to compare various neutron damage parameters for samples irradiated in CTR and SNS. Several theoretical studies have been conducted for gas deposition characteristics of different designs of CTRs [3,4]. The aim of the present paper is to study helium and hydrogen deposition in samples irradiated in an SNS and compare the results with those of a CTR. As a reference design for an SNS we have chosen a proposed spallation neutron source called “EURAC” which is based on a 600 MeV beam of protons impinging on a liquid lead target. For this design of SNS we have carried out detailed evaluation of helium and hydrogen deposition in samples of Fe. We have also evaluated neutron and proton fluxes and their spectra using the high energy transport code HETC and studied the effect of variation in sample position on hydrogen deposition. The results of these calculations show that the helium and hydrogen deposition are very sensitive to the high energy part of the neutron spectrum in EURAC. It is also shown that more than half of the total helium production in the irradiation of a sample of Fe is due to neutrons above 40 MeV even though these neutrons constitute only about 3% of the total neutron flux. The results also show that most of the hydrogen deposition is due to the slowing down of secondary protons in the sample.

Identification of salt—Alloy combinations for thermal energy storage applications in advanced solar dynamic power systems

Thermodynamic calculations based on the available data for flouride salt systems reveal that a number of congruently melting compositions and eutectics exist which have the potential to meet the lightweight, high energy storage requirements imposed for advanced solar dynamic systems operating between ∼1000 and 1400 K. Compatibility studies to determine suitable containment alloys to be used with NaF-22CaF2-13MgF2, NaF-32CaF2, and NaF-23MgF2 have been conducted at the eutectic temperature + 25 K for each system. For these three NaF-based eutectics, none of the common, commercially available high temperature alloys appear to offer adequate corrosion resistance for a long lifetime; however mild steel, pure nickel and Nb-1Zr could prove useful. These latter materials suggest the possibility that a strong, corrosion resistant, nonrefractory, elevated temperature alloy based on the Ni—Ni3Nb system could be developed.