Mechanical Properties Of Niobium Research Articles

The Investigation of Mechanical Properties of Polycrystalline Nb Nanowire Under Applied Tensile Deformation by Molecular Dynamics Simulation

In this study, the change in the mechanical properties of Niobium (Nb) nanowire with different grain numbers under applied uniaxial tensile deformation was tried to be investigated by Molecular Dynamics (MD) simulation method. The Embedded Atom Method (EAM), which includes many-body interactions, was used to determine the force interactions between atoms. To determine the effect of grain number on the mechanical properties of Nb nanowire, stress-strain curve, young modulus, yield strain and atomic images obtained from the common neighbor analysis method (CNA) were used. It has been determined that necking and breaking of the model nanowire occur at the grain boundaries, however, the number of grains has important effects on the mechanical properties.

Effect of oxygen on microstructure and mechanical properties of niobium

The effect of oxygen on microstructure and mechanical properties of niobium has been investigated. Niobium samples containing 50–800wt.ppm oxygen have been prepared by absorption and diffusion techniques. The samples were characterised with respect to chemical composition, microstructure and mechanical properties. Niobium containing up to 800wt.ppm of oxygen exhibited essentially single phase microstructure with no precipitates. The hardness and strength increase with increase in oxygen content. The increase in strength is marginal up to 400wt.ppm oxygen and significant from 400 to 800wt.ppm oxygen.

ニオブの圧縮変形特性に及ぼすタングステンおよびモリブデンの添加効果

The alloying effects of tungsten (W) and molybdenum (Mo) on the mechanical properties of niobium (Nb) have been investigated by means of Vickers hardness test and cold upsetting test. It is found that the alloying effects of W and Mo on the Vickers hardness for the as-cast samples are nearly the same and the hardness increase almost linearly with increasing the total amount of alloying elements, W and Mo. The compressive yield stress of the binary and ternary alloys also increase almost linearly with increasing the amount of the alloying elements into Nb. On the other hand, the alloying effects of W and Mo on the work hardening behavior of the alloys appear to be different. For example, the flow stress of Nb-5 mol%W alloy is higher than that of Nb-5 mol%Mo alloy after yielding in the upsetting test. In fact, the work hardening exponent, n, in the power low is larger for Nb-5 mol%W alloy than Nb-5 mol%Mo alloy.

A New Concept for Alloy Design of Nb-Based Hydrogen Permeable Alloys with High Hydrogen Permeability and Strong Resistance to Hydrogen Embrittlement

A concept for alloy design of Nb-based hydrogen permeable alloys has been proposed based on the mechanical properties of niobium in hydrogen atmosphere and also on the hydrogen chemical potential in metal membrane. Following this concept, Nb-based alloys are designed and developed that possess excellent hydrogen permeability without showing any hydrogen embrittlement.

Effects of Structural Behavior on Electromagnetic Resonance Frequency of a Superconducting Radio Frequency Cavity

AbstractDuring operation, a superconducting radio frequency cavity is cooled down to below critical superconducting temperature by liquid helium. Thus it is under external pressure by liquid helium while an ultrahigh vacuum inside. Being a niobium-made shell structure, the SRF cavity's shape and consequently the electromagnetic resonance frequency are sensitive to external load variations. A CESR-III 500MHz superconducting radio frequency cavity is illustrated to investigate this relationship. A simulation that links the calculations on mechanical structure and radio frequency electromagnetic field with the finite element code ANSYS® is demonstrated herein. The changes of electromagnetic resonance frequency associated with external loads and mechanical properties of niobium are studied systematically. A complete understanding on the mechanism is thus achieved. The computed results also indicate that the electromagnetic resonance frequency increases as the cavity is either cooled to cryogenic temperature or stretched longitudinally, while the reduction of the helium vessel pressure also raises the resonance frequency. Besides, the electromagnetic resonance frequency shift is ruled by the coefficient of thermal expansion when the cavity is cooled from room temperature to liquid helium temperature. Young's modulus and thickness of the cavity wall dominate the structure stiffness and thus also affect the frequency shift.

Effect of Water Vapor/Hydrogen Environments on Niobium, B-66 Niobium Alloy, Tantalum, and Ta-10W Alloy

Abstract The results of an experimental investigation of the effect of water vapor/hydrogen environments on the mechanical properties of niobium, B-66 niobium alloy, tantalum, and Ta-10W alloy are presented. Tensile tests were conducted on specimens of these materials in water vapor/hydrogen environments with water vapor/hydrogen mixture ratios of 1 and 3. The water vapor/hydrogen environment caused strength reductions on tantalum and Ta—WW and ductility reductions on all four materials. The degree and causes of embrittlement were a complex function of temperature.

Hydrogen treatment of niobium: Strengthening and structural changes

A review on the phenomenon of controllable hydrogen phase naklep and the prospects of its use in metal science and engineering was published in this journal in 1981. In the review we covered both the scientific and practical aspects of the new experimentally discovered phenomenon of the controllable transition of metals and alloys into a high strength state with special physical properties by charging them with hydrogen and causing α solid solution ⇌ hydride β phase transformations. We called this phenomenon “controllable hydrogen phase naklep” (HPN). The HPN phenomenon has been demonstrated in a limited number of metals and alloys under a variety of conditions. Palladium is the classic material for studying this phenomenon. We assume that HPN is a general phenomenon which may be exploited for many alloy systems. The main idea of this work is to confirm the HPN phenomenon in a specific material, i.e. niobium, which is very sensitive to embrittlement and is not a polymorphic material. This is why there are few possibilities to treat niobium, to change its structure and to improve its properties. First we consider the main features of the HPN phenomenon and the reasons why it is not correct to use the terms “cold work”, “strain hardening”, “cold hardening” and others for this new general phenomenon. Data are given for the special vacuum-hydrogen installation and the experimental technique of hydrogen treatment which causes controllable phase naklep of niobium with its plasticity preserved. This is followed by a review of hydrogen treatment results. The possibilities to have a great variety of structures and mechanical properties of niobium and niobium-hydrogen alloys after hydrogen treatment causing HPN are obvious. Finally, new ideas about the phenomenology and mechanism of the phenomenon are discussed.

Effect of titanium on the mechanical properties of niobium at low temperatures

Niobium has satisfactory ductility and is not susceptible to brittle fracture at low temperatures. The alloy of Nb+5.5% Ti is sensitive to stress concentrations at 20°K.

The influence of long, high-temperature holds on the structure and mechanical properties of niobium and NV-7 alloy

The influence of long, high-temperature holds on the structure and mechanical properties of niobium and NV-7 alloy

Effect of Neutron Irradiation on Mechanical Properties of Niobium and Nb-Y Alloy

Effect of Neutron Irradiation on Mechanical Properties of Niobium and Nb-Y Alloy

Effect of Neutron Irradiation on Mechanical Properties of Niobium and Nb-Y Alloy

Effect of Neutron Irradiation on Mechanical Properties of Niobium and Nb-Y Alloy

Effect of interstitial impurities on the mechanical properties of niobium and its alloys

1. The mechanical properties of niobium and its alloys depenet to a considerable extent on their content of interstitial impurities at both low and high temperatures; this opens up the possibility of alloying with such impurities finished components of niobium and its alloys in order to obtain the best combination of strength and ductility in each particular case. 2. The results of long-term strength tests on alloy 5VMTsU at 1100°C in vacum of 10−5 and 10−8 mm Hg have shown that the strength of this alloy on a basis of 800 h falls by 49% in a vacuum of 10−8 mm Hg.

Mechanical properties of niobium alloyed with elements of groups IVa?VIa

1. A fairly substantial increase in the strength of niobium at room temperature, with satisfactory ductility, is obtained by alloying with small quantities (0.5–2 at. %) of elements from groups IVa–VIa. 2. The increase in strength due to different elements differs and depends under the conditions investigated on the difference in the atomic size of niobium and the alloying element and also its activity with respect to interstitial impurities (the latter in the case of insufficiently pure "binary" alloys).

Neutron Irradiation Effects on Mechanical Properties of Niobium

KEYWORDS: irradiationradiation effectsstressestemperature dependencemechanical propertiesniobiumneutron beams dislocation channelingtransmission electron microscope

Neutron Irradiation Effects on Mechanical Properties of Niobium

Neutron Irradiation Effects on Mechanical Properties of Niobium

The effects of interstitial solute additions on the mechanical properties of niobium and tantalum single crystals

The influence of binary and ternary additions of oxygen and nitrogen on the mechanical behavior of niobium and tantalum single crystals has been investigated. Additions of either oxygen or nitrogen to high-purity crystals cause only alloy hardening in both the thermal and athermal temperature regimes. The same additions to less pure crystals or to high-purity crystals intentionally doped with a second interstitial, result in alloy softening in the thermal component of the yield stress. The strain rate sensitivity varies with interstitial content in the same manner as the yield stress, whether alloy hardening or softening is observed. These results are interpreted in terms of effects that solute interactions exert on thermallyactivated interstitial hardening in niobium and tantalum.

Mechanical properties of niobium and niobium alloys at low temperatures

Mechanical properties of niobium and niobium alloys at low temperatures

Effect of purity on the mechanical properties of niobium

The change in the mechanical properties of cold-swaged niobium reduced 90% in cross-section was investigated on isochronal annealing before and after electronbeam zone melting. It was found that zone-melted niobium has 1. (a) greater ductility, 2. (b) greater uniform elongation, 3. (c) increased work hardening, but 4. (d) lower strength. Furthermore, zone-melted niobium shows, after swaging and in the temperature range 20–700°C, a yield point. For both kinds of niobium increased strength was found between 400°C and 600°C and attributed to the influence of carbon in the samples.

The effect of high vacuum purification on the mechanical properties of niobium single crystals

The effect of high vacuum purification on the mechanical properties of niobium single crystals

Effect of alloying on the mechanical properties of niobium

The effects of additions of those elements which are near neighbors in the periodic table on the mechanical properties of niobium have been studied. These effects vary widely and follow no simple general rule. Some of the most important observations are as follows: 1. (1) At low temperatures alloy additions increase strength due to normal solid-solution strengthening and by raising the range over which strength becomes strongly temperature-dependent. The fracture transition temperature range is raised, in part due to the strength increase and in part due to changes in fracture characteristics. When compared at equal atom percentages, the group tungsten-molybdenum exert the greatest increase in fracture transition temperature; titanium and hafnium have relatively little effect; and zirconium and vanadium are intermediate. 2. (2) When compared at room temperature, equal atom percentages of vanadium and chromium appear to give the largest increase in strength; titanium and hafnium the smallest; and the remaining elements are intermediate. With the purity, grain size and test procedures used here, additions of over 10 w/o molybdenum or tungsten resulted in very low room-temperature ductility. 3. (3) At 1095°C when compared at equal atom percentages, zirconium and vanadium show the largest increase in strength; titanium has very little effect; molybdenum, tungsten and hafnium are intermediate strengtheners. Limited data on chromium indicate it to be a potent strengthener. 4. (4) No single alloy addition confers the best combination of mechanical properties. Elements like molybdenum and tungsten, which confer reasonably good increases in low- and high-temperature strength, result in a significant increase in the low-temperature fracture transition. Titanium strengthens at low temperature with very little effect on fracture transition but has very little effect on high temperature strength. Zirconium and hafnium appear to be somewhat intermediate in their effects on low- and high-temperature strength and ductility. On the basis of workability, low-temperature ductility, and elevated temperature strength, vanadium additions appear to be very attractive. The only apparent disadvantage is the hot shortness condition observed in the 20 w/o V alloy. 5. (5) Interstitial elements appear to exert a very pronounced effect on the elevated temperature properties of certain niobium-base alloys.