Small Amount Of Zr Research Articles

Structures and properties of a Zr-based bulk glass alloy after annealing

A bulk glass Zr 52.5 Ni 14.6 Al 10 Cu 17.9 Ti 5 alloy with 6 mm diameter is prepared by pre-melting sponge zirconium together with other pure metal elements and followed by injecting cast. In the samples, the content of oxygen is chemically analyzed in the level of 706 ppm (atomic concentration), which significantly affects the crystallization and the microstructure. When the bulk glass samples are annealed at the temperature far below the crystallization temperature( T x ), the predominant phases of Zr 2 Ni 0.67 O 0.33 and Zr 2 Ni compounds crystallize and uniformly distribute on glass matrix. These predominant phases will grow and join together to form net-shape phase when the annealed temperature is in the range of T x to above T x . The glass matrix phase separated by the net-shape phase into the size of about 25 μm at 703 K to 15 μm at 823 K almost fully transforms into Zr 2 Ni and a small amount of Zr 2 Cu and Zr 4 Al 3 . At annealing temperatures far above T x , Zr 2 Cu and Zr 4 Al 3 compounds crystallize by phase separation to form nanostructure with nano-scale phases of Zr 2 Cu and Zr 4 Al 3 compounds distributed on the matrix of Zr 2 Ni. The micro-compressive tests by Nanoindenter II reveal that the bulk glass phase has a lower elastic modulus and lower microhardness. Increasing the annealing temperature, the modulus and microhardness for the crystallized microstructure increase. With the phase separation taking place, the modulus and microhardness for the nanostructure are improved slightly. But the different deformational mechanism between micro-scale and bulk specimens is unknown.

The cyclic oxidation behaviors of Fe3 (Al, Cr, Zr) and Fe3 (Al, Cr, Nb) intermetallic compound at high temperature

The cyclic oxidation behaviors of Fe-28Al-5Cr-O. 1Zr (at%) and Fe-28A15Cr-O. 5Nb (at%) alloys have been investigated in air at high temperature. The results show that the distinctive whisker-like oxides were formed on the surface of Zr-containing Fe3 Al based alloy after 500 hrs. cyclic oxidation at 800 °C and 1000 °C. The results also indicate that the addition of small amount of Zr to Fe3 Al based alloy can improve its adherence strength between the oxides and metal substrate and is beneficial to the oxidation resistance. However, for the Nb-containing Fe3 Al based alloy, porous convoluted oxides were formed after 350 hrs. cyclic oxidation at 1000°C, and this type of oxides didn’t not contribute to the oxidation resistance.

ＺｒおよびＴｉにより結晶粒微細化したＡｌ‐Ｌｉ‐Ｍｇ鋳造合金の組織と機械的性質

Mechanical properties and microstructures of various Al-Li-Mg alloy castings containing small amount of Zr and/or Ti were investigated. The δ (AlLi) phase was observed to crystallize in the dendrite-cell gaps as well as on the grain boundaries. Microsegregation of Mg also occured in the solidified castings. The β (Al3Zr) or Al-Zr-Ti compounds crystallize during solidification and remain even after solid solution treatment at 803K for 36ks. The grain sizes of Al- 2.5%Li-2%Mg alloy castings become finer by the addition of 0.15%Zr and 0.12%Ti compared with each addition of 0.15%Zr or 0.12%Ti. The age hardning is accelerated by the addition of 0.15%Zr. In an Al-2.5%Li-2%Mg-0.15% Zr-0.12%Ti alloy casting poured into a metallic mold and aged at 453K for 36ks, ultimate tensile strength, Young's modulus and density were 417MPa, 80GPa and was 2.52g/cm3, respectively. Its specific strength and modulus are higher by 50.3 and 13.9% than those of the conventional AC4C-T6 casting.

Interfacial studies in Nb3Sn superconductors

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.

HREM of Rapidly Solidified Al-Li-Zr Based Alloys

During aging of Al-Li-Zr based alloys δ'(Al3Li) precipitates heterogeneously around β'(Al3Zr), forming so-called composite precipitate[l-4], that has important effects on the mechanical behavior of these alloys. As has been observed in several investigations, the addition of small amount of Zr results in a fairly large volume fraction of β' in the microstructure, and this suggests that there may be a partitioning of Li in the β'. In the present investigation, high resolution electron microscopy (HREM) and image simulation have been used to perform detailed characterization of the chemistry and structure of β' precipitate.The alloy Al-3Li-1Cu-0.5Mg-0.5Zr (wt.%) has been heat treated as follows: a) solution treatment at 550°C for 2 hours and water quenching, b) aging treatment at 150°C for 4 hours or at 200°C for 8 hours and c) 10% cold working followed by aging at 175°C for 64 hours. HREM images were taken on a JEOL ARM electron microscope operating at 400 and 800kV. Simulated HREM images of the composite δ'/β' precipitate were calculated using CEMPAS multislice program described by Kilaas[5].

Metal Hydride Anodes for Nickel‐Hydrogen Secondary Battery

It has been found that the respective substitutions of La and Ni in by small amounts of Zr and Al remarkably improved the cycle life of the alloy anode, scarcely causing a lowering of capacity. In order to clarify the mechanism, the relations between chemical compositions and anode properties for , such as capacity, cycle life, rate capability, temperature behavior, and self‐discharge character, were examined. With increasing Zr content in the presence of the cycle life (CL) increased greatly: for , for , for , and for . The self‐discharge was also depressed by the Zr addition. However, hydrogen overpotentials showed a tendency to increase with increasing Zr content, leading to the lowering of discharge potentials and capacities at high currents and low temperatures. The results obtained here were discussed in terms of surface oxide film which worked as a barrier for preventing the diffusion of hydrogen and for protecting the alloy from further corrosion. It was suggested that the small amounts of substituted Zr and Al play an important role by getting the surface oxide film more dense and protective.

耐熱鋳鋼のクリープ・疲労特性におよぼす組織と力学因子について

Low cycle fatigue (LCF) and fatigue crack propagation (FCP) tests under creep conditions were carried out on HK40, HP, and their modified alloys containing a small amount of Zr, Nb, and/or Ti. The failure mechanism was established based on the microscopic observations by the scanning and transmission electron microscopies. Also, the mechanical factors affecting the LCF life were discussed, considering the crack propagation law. The main results obtained are as follows;(1) The addition of Nb, Ti and/or Zr improves the LCF life and the FCP resistance under creep conditions. In particular, the effect of Zr is marked.(2) Cracks propagate along the intensive sub-boundaries, on which coarse M23C6 carbides precipitate during the LCF test.(3) Zirconium, Nb and Ti form fine and dispersed secondary carbides (MC) in the matrix of material. These fine carbides lead to a uniform dislocation structure without intensive sub-boundaries and then result in the dispersed precipitation of coarse M23C6 carbides. Accordingly, the addition of these elements improves LCF and FCP properties.(4) From a mechanical viewpoint, the LCF life can be determined by the fatigue and creep crack propagation laws and the strain energy densities which are obtainable based on J-integral analysis on a cracked body.

Magnetostriction Constants of High Bs CoZr Amorphous Films

The effect of small amounts of Zr in CoZr films is discussed. It was found that a Zr concentration of 4 at% or less caused the magnetostriction constant to decrease to 1 × 10?6. The magnetostriction constant was measured by making one edge of the film stationary, applying a 20 Oe magnetic field in the easy and hard axis directions and measuring the displacement of the free edges. The magnetorestriction constant of films with a Zr concentration of 4.8 at% and with various film thickness was nearly constant (it was somewhat smaller for thinner films), but after heat treatment this constant decreased without saturating. The value decreased with decreases in the Zr concentration. The magnetostriction constant of CoZr films with a Zr concentration of 3.4 ~ 4 at% decreased to approximately 1 × 10?6.

Neutron and X-ray diffraction study of Y<inf>2</inf>Co<inf>17-x</inf>Zr<inf>x</inf>and Y<inf>2</inf>Co<inf>17-y</inf>Mn<inf>y</inf>compounds

The ternary Y <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Co <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</inf> -based systems in which Co is replaced by Zr and Mn have been studied by neutron diffraction, X-ray diffraction and magnetic measurements to ascertain the effect of the substitution on their crystallographic properties and magnetocrystalline anisotropy. The x-ray diffraction and magnetic measurements showed that in Y <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Co <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</inf> the easy magnetization direction lies in the basal plane, however, in the ternary Y <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Co <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17-x</inf> Zr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> and Y <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Co <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17-y</inf> Mn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> compounds, a change of the direction of easy magnetization occurs with a small amount of Zr and Mn. From the neutron diffraction results we found that the Zr and Mn atoms prefer to occupy the 6c sites. This is the reason that the easy magnetization direction changes from basal plane to the c-axis.

Optical Properties of Ag-Based 4d-Transition Metal Alloys

The dielectric constants of Ag-based alloys with a small amount of Zr, Nb and Mo are evaluated from measurements of reflectances and transmittances of thin films prepared by simultaneous evaporation in vacuum for photon energies between 0.55 eV to 5.63 eV. The dc resistivities and the thermoelectric powers of the films are also measured. An additional absorption band due to the presence of the virtual bound state is observed for all alloy systems. The data are compared with the calculation based on the Friedel-Anderson model. The positions of the virtual bound states of the alloys are estimated.

Influence of Some Additional Elements on the Aging Kinetics in Al&amp;ndash;Cu and Al&amp;ndash;Cu&amp;ndash;Mg Alloys

Aging kinetics in Al-1.9 at%Cu and Al-1.9 at%Cu-1.7 at%Mg alloys containing small amounts of Zr, Cr, Mn, Ag and Cd have been investigated by the measurements of electrical resistivity and hardness and also by electron microscope observations.The addition of Zr, Cr or Mn retards the clustering of solute atoms in Al–Cu and Al–Cu–Mg alloys and then reduces the age-hardening when these elements are finely distributed as the insoluble compounds. This effect can be reasonably explained by a similar mechanism to that of Al–Zn and Al–Zn–Mg alloys, that is, in terms of the increase in vacancy sinks rather than the decrease in supersaturated solute atoms or the existence of binding energy between a solute atom and a vacancy.The aging kinetics in Al–Cu alloys are little affected by the addition of Ag, despite the well-known fact that Cd reduces remarkably the rate of G. P. zone formation and stimulate the nucleation of intermediate precipitates. This is probably due to the reason that the clustering of Cu atoms takes place on the {100} matrix plane, whereas Ag atoms cluster on the {111} plane and do not participate in the G. P. zones of Cu atoms. The additions of these elements to Al–Cu–Mg alloys decrease the rate of clustering but increase the age-hardening at high temperature. This may be due to the participation of Ag or Cd atoms in G. P. zones of Cu and Mg atoms.

On the casting and the recrystallization of Al and some Al alloys containing Zr

99.99%, 99.5%Al and several kinds of Al alloys containing small amounts of Zr were studied on the casting structure and recystallization by means of hardness measurments, X-ray methods and tensile testings. Results obtained were as follows:1) 99.99%Al-Zr alloy had refined casting grains for Zr content of more than 1%, and had high recrystallization temperature.2) 99.5%Al-Zr alloy had a high recrystallization commencing temperature, which was 400°C in case of 0.3%Zr, and had refined grains for Zr content of more than 0.5%3) Si had a marked effect on the recrystallization temperature of pure Al-Zr alloys.4) Zr had small effect on the recrystallization temperature of Al-5%Mg alloy, but a marked effect on refining of the grain5) Al-0.1%B-0.58%Zr alloy had a very high recrystallization temperature and perfectly refined equiaxial grains6) 52S-and 61S-Zr alloys had a little higher recrystallization temperature respectively when worked by 50%. Their corrosion resistance, however, were not changed by the addition. Zr.