been investigated. The measurements of electrical resistivity, magnetic and low-temperature speciﬁc heat capacity have been carried out. Furthermore, the band calculations by using the tight-binding linear muﬃn-tin orbital (LMTO) method based on the local spin density approximation (LSDA) with the coherent potential approximation (CPA) have been performed. In addition, the LMTO band calculations includ- ing the spin–orbit interaction have been carried out in order to discuss the relation between the magnetocrystalline aniso- tropy energy and the spin structure. Characteristic antiferro- magneticproperties associated with a pseudo-gap in the electronic structure emerge in the present study. The main results are summarized as follows:
Metallic glasses consist of 3d transition metal elements (Cr, Mn, Fe, Co, Ni) and high valence elements (B, Al, Si, P, C, etc.) which are opaque, ductile and good con- ductors of electricity and heat. Metallic glasses show amorphous structures with a non equilibrium state, so the amorphous phase can be transfer to a stable equilibrium state by the rise of temperature. There are a number of experimental evidences which indicate that the amor- phous structure is crystallized above a certain tempera- ture [1,2]. Crystallization involves a change in properties such as structural, heat capacity, electrical resistivity and magnetic, etc. . Amorphous and nanocrystalline Fe base metal alloys have been attracted both for experi- mental and theoretical researchers in the fields of solid state physics, electronics and electrical engineering [4-8]. The (Fe 1–x Mn x ) 75 P 15 C 10 alloys are soft magnetic which
DOI: 10.4236/ampc.2018.810027 402 Advances in Materials Physics and Chemistry of rare earth secondary phases, and is observed for only few kind of rare earth elements . It is well known that the magneticproperties of the ferrite mate- rials depends on the type, ionic radius and concentration of the doping ions (magnetic/nomagnetic nature) , grain and morphology of the samples and methods of preparation  . Doping these ferrites with various transition elements leads to important changes in their structural, electrical and magneticproperties.
INFLUENCE OF COMPOSITION ON THE STRUCTURE, ELECTRIC AND MAGNETIC PROPERTIES OF Pd Mn P AND Pd Co P AMORPHOUS ALLOYS Thesis by Neville Ingersoll Marzwe11 In Partial Fulfillment of the Requirements for[.]
important factor for the application of these materials, has to be evaluated as well. As have been reported before, the uniform distribution of atoms establishes a strong tendency of uniform corrosion on the amorphousalloys that exhibit better corrosion resistance than their counterpart alloys. 1012) Air-formed native oxide ﬁlms help maintaining passivation, and decreasing corrosion rates, and have a positive effect on the corrosion properties of Fe 83.3 Si 3 B 10 P 3 Cu 0.7 ribbons in
described about the electron diﬀraction patterns in insets of Fig. 3, -Fe grains are dispersed randomly. In addition, it can be recognized that the morphology of -Fe grains has an oval shape rather than a circular one from Figs. 3 and 4. A remarkable feature is that the intergranular amorphous phase exists in both alloys.
The discovery of Heusler alloys dates back to 1903 when Heusler reported that the addition of sp elements (Al, In, Sn, Sb or Bi) turn Cu-Mn alloy into a ferromagnetic material even though the alloy contains none of the ferromagnetic elements. The basic understanding of crystal structure and composition of these alloys remained unknown for a long time. In 1929 X-ray measurements of Potter on Cu-Mn-Al alloy revealed that all constituents of this system was ordered on an fcc super lattice. Bradley and Rodgers investigated Cu-Mn-Al system in detail using X-ray and anomalous scattering. The authors established a relationship between composition, chemical order and magneticproperties. Heusler compounds are an interesting class of compounds with wide-ranging and tunable properties. They are intermetallic compounds with the general composition X 2 YZ, where X and Y are transition
For the evaluation of zirconium-base amorphousalloys as biomaterials, the surface compositions of amorphous Zr–Al–Ni–Cu and Zr–Al– Cualloys were characterized using X-ray photoelectron spectroscopy. The alloys were polished, autoclaved, and immersed in Hanks’ solution or Eagle’s minimum essential medium containing fetal bovine serum, MEM + FBS. Aluminum was enriched in the surface oxide film and the substrate just under the film of the alloys polished in water. After autoclaving, aluminum and copper were enriched in the substrate while zirconium was preferentially oxidized and incorporated into the surface oxide film. In Hanks’ solution, copper and nickel decreased in the substrate and surface oxide film, resulting in the enrichment of aluminum in the substrate. In MEM + FBS, zirconium preferentially decreased by the effects of amino acids and proteins while copper was enriched in the substrate. The surface composition of zirconium-base amorphousalloys was much influenced by amino acids and proteins in MEM + FBS.
In order to conﬁrm the detailed microstructure of the 1% and 3% Ta-containing as-cast rods, TEM and HREM were also carried out. Figure 7(a) shows the HREM and bright TEM images as well as the corresponding selected area diﬀraction patterns (SAED) of the 1% and 3% Ta-containing alloys. The HREM image of the 1% Ta-containing rod shows that some nano-particles with a size smaller than 5 nm disperse in glassy matrix in Fig. 7(a). With 3% Ta addition, nano-particles are much larger (Fig. 7(b)). The selected area diﬀraction pattern is composed of several ring patterns superimposed on a diﬀuse halo patterns, implying a mixture of nano-particles and glassy matrix. Combining with the results of XRD, it is concluded that the nano-particles are Ti 3 Cu 4 phase.
The stress relaxation behavior and cluster distributions in a Cu-P alloy and two Cu-Ni-Palloys with diﬀerent P content have been investigated by means of 3DAP. No clusters were observed in the Cu-0.10P (mass%) alloys, in either the cold- rolled and annealed conditions, nor in the Cu-0.39Ni-0.006P (mass%) alloy in the cold-rolled condition. The three materials showed similar stress relaxation performance, although dislocation pinning by solute P can be expected to occur in the Cu-Palloys. On the other hand, the Cu-Ni-P alloy formed a low density of Ni-P clusters during annealing in spite of low P content, and showed a greater improvement in stress relaxation resistance than the Cu-P alloy. Therefore, it is concluded that the pinning eﬀect of solute P has much less impact on the stress relaxation behavior in Cualloys than the eﬀect of the clusters.
alloys with a weight of 10 mg (1 mm in thickness). Figure 2 shows the high-resolution TEM images, and selected-area electron diffraction patterns (SADPs) taken from a part of ap- proximately 100 nm in diameter. Although the image in Fig. 2(a) contains some areas revealing a lattice fringe-like con- trast, most parts in the image are occupied by non-periodic contrast. Furthermore, the SADP in Fig. 2(a) consists only of halo rings and no appreciable reflection spots from crystalline phases are seen. These results indicate that an amorphous phase is formed in this alloy. In contrast to Fig. 2(a), the im- ages in Figs. 2(b) and (c) show distinct lattice fringes, and the corresponding SADPs give reflection spots. From the images shown in Figs. 2(b) and (c), the mean diameter of the lattice fringe regions is estimated as more than 20 nm for the x = 5 alloy, and approximately 5 nm for the x = 10 alloy. The dif- ference in the region size for these alloys can be recognized in their SADPs as in the case of the difference in the number of
only the strength but also workability and fatigue character- istics. In this study, aging conditions under which hardness was highest (250 Hv or higher) and the conductivity exceeded 20% IACS were present in both alloys: with or without added N, when aging at 420°C: for the Cu-Ti-N alloys, aging at 420°C resulted in the conductivity exceeding 20 % IACS (22 % IACS for a Cu-Ti-0.6N alloy) at the aging time corresponding to the maximum hardness. On the other hand, the conductivity of the Cu-Ti alloys without N did not reach 20% IACS at the aging time corresponding to the maximum hardness, but reached it after over-aging for 240 h. Thus, in the case of Cu-Ti-N alloys, it is possible to realize aging materials with cellular components not yet developed having a Vickers hardness of 250 Hv or higher and a conductivity of 20% IACS or higher. Decrease in the maximum hardness due to N addition is an issue that needs to be addressed. However, it can be said that one of the effective additive elements is N that can improve the balance between workability and conductivity, as well as provide optimum structure control when an appropriate amount of N is added in the Cu-Ti alloys.
The catalytic performances of samples were investigated in the hydrogen generation from ammonia borane. aCuTi was totally-inactive in this reaction. The amount of evolved hydrogen over s-Cu(300) was larger than that of the other samples, as shown in Fig. 5. The s-Cu(400) exhibited a lower catalytic activity than s-Cu(300) despite the highest surface area of s-Cu(400). The catalytic activities per surface area were shown in Fig. 6 to investigate the effect of the atomic arrangement of Cu-Ti amorphous alloy on the catalytic activity of skeletal Cu. The s-aCu showed the highest catalytic activity per surface area. The catalytic activity per surface area decreased with increasing heating temperatures to aCuTi. For further consideration, the crystallinity of s-aCu and s-Cu(600) were measured by XRD. As shown in Fig. 7, three peaks are observed, and they were assigned to the Cu phase and Cu 2 O phase which caused by the exposure to air of
One characteristic feature of a Ti-(50-x)Pd-xFe alloy (7 x 16) is that its electrical resistivity exhibits a negative temperature coeﬃcient (NTC) above its martensitic transformation start temperature. Another characteristic feature is that diﬀuse satellites appear at incommensurate positions in electron diﬀraction patterns observed in the temperature range of NTC in electrical resistivity. From these observations, Enami et al. interpreted that a Ti-(50-x)Pd-xFe alloy exhibits a premartensitic transformation at the temper- ature where the resistivity shows a local minimum. The diﬀuse satellites in the premartensite state were then conﬁrmed to appear by Ii et al. 8) and Murakami et al. 9) by
tains incompleteness. The reason for the incompleteness was assumed that the parameter did not take the structural factor of primary precipitation into consideration. With the aim of evaluating more accurately GFA for off-eutectic alloys, we introduced the modified T g / T l , which can be regarded as the
Studies on metallic amorphousalloys and their functional properties have been an important subject for scientists and researchers during the last two decades. This has been attributed to novel mechanical, 1–4) magnetic 5–8) and cataly- tic 9–11) properties and excellent corrosion resistance 12–17) for these materials. Among magneticamorphous materials, Co- based alloys are important and have been produced by various techniques including rapid quenching, 18,19) physical vapor deposition, 20) chemical or electroless plating 21,22) and electrodepostion. 23–29) The alloys produced by electrodepos- tion include Co–P, Co–W and Co–Ni–P etc. It is known that these Co-based magneticalloys have relatively low satura- tion magnetization values below 1.0 T. Recently, Myung et al. 30) have produced Co–Ni–P crystalline alloys having high cobalt and low phosphorus contents. It has been characterized that these alloys exhibit rather high saturation magnetization in the range of 1.2 to 1.4 T. In this work, we examine optimum conditions for the formation of amorphousalloys with relatively high saturation magnetization values up to about 1.2 T from a similar electroplating solution.
applied at first by Akinlade et al  to two segregating alloys, Bi-Zn and Cu-Bi and later O. E. Awe applied it for four liquid alloys . In the present paper, we employed the same empirical model of Singh and Sommer and darken thermodynamic equation of diffusion to investigate the effect of size on the transport properties of two copper based alloys (i.e.Cu-Sb and Cu-Sn). Our choice of these two alloys was based on the fact that they are examples of alloys where size mismatch between atom-A and atom-B in each of the alloys is considered to be significant . That is the volume or size difference between atom-A and atom-B does not lies within 50 percent and, hence, the difference is not negligible, i.e.at the melting points, in Cu-Sb, Sb atom is 2.56 times bigger than the Cu-atom and in Cu-Sn, Sn atom is 2.29 times bigger than Cu-atom . In addition we are also aware that the two alloys represent the distinct classes of binary liquid alloys, namely, class of alloys that exhibit negative deviation from raoult’s law of linearity, known as hetero-coordinated or short-ranged ordered alloys. Another reason for choosing to work on these alloys is that each of the two alloys has either an interesting features or is industrially relevant.
Thus, the Pd-Cu-Si metallic glassy alloy is expected to show excellent properties for the hydrogen sensor. As we mentioned above, hydrogen sensing ability and stability are key requirements for the hydrogen sensor of fuel cell vehicles. As for hydrogen sensing ability, large response to hydrogen is naturally required for accuracy of the hydrogen sensor. As for stability, we focused on the thermal stability in this study. A metallic glassy alloy is a kind of amorphous alloy and it will crystallize gradually by receiving heat. If amorphous phase is transformed into crystalline phase, its resistivity also changes causing inaccuracy of the hydrogen sensor. Therefore, higher T g and T x (T x : crystal-
The band structures and DOS plot show that the transition metals have partially filled d-shells and their d- bands extend through the Fermi surface. Since the d-bands are narrow and contain more levels than free electron bands, the density of states at the Fermi level become very high. The magnetic moment is due to asymmetric distribution of d bands in the fermi level. The density of states of up and down spins for Fe, FePd and Fe 3 Pd are found to be quite asymmetric in nature which causes a net magnetic moment and thus