Effect Of Additional Elements Research Articles

Effects of additional elements on hydrogen absorption and desorption characteristics of Sm 2Fe 17 compounds

Effects of additional elements on hydrogen absorption and desorption characteristics of Sm 2Fe 17 compounds have been studied. On heating the Sm 2Fe 17 compound under an atmospheric pressure of hydrogen, the Sm 2Fe 17 compound disproportionates into a mixture of SmH 2 and α-Fe at around 550 °C; this mixture recombines to form the original compound above 1000 °C. Zr or Nb addition makes the disproportionation reaction sluggish. Co or Ga addition decreases the temperature of the recombination reaction under an atmospheric pressure of hydrogen. It can be said that Co or Ga addition is effective for enhancing the recombination reaction in hydrogenation, disproportionation, desorption and recombination phenomena.

Effects of additives on hydrogenation, disproportionation, desorption and recombination phenomena in Nd 2Fe 14B compounds

Hydrogenation, desorption, disproportionation and recombination (HDDR) phenomena are very attractive for the production of anisotropic NdFeB powders with high coercivity. HDDR phenomena are closely related to the characteristics of hydrogen absorption and desorption which correspond to the disproportionation and recombination reactions respectively. The effects of additional elements on these characteristics have been studied. According to the results for Nd 12.6Fe 81.4B 6.0 alloys, Nd 2Fe 14B compounds disproportionate into a mixture of NdH 2, α-Fe and Fe 2B phases at around 650 °C, which recombine to give the original compound at around 1050 °C under atmospheric pressure of hydrogen. The Nd 2Fe 14B compound exhibits two hydrogen desorption peaks corresponding to the recombination reaction. Judging from this result, it is considered that the recombination reaction occurs by a two-stage process. The temperature of the hydrogen absorption peak corresponding to the disproportionation reaction shifts to a higher value on the addition of Zr. Alloys with Co or Ga added show lower optimum temperatures of the recombination reaction than those of the alloy without additional elements. It can be said that Zr addition makes the disproportionation reaction sluggish, and Co or Ga addition enhances the recombination reaction in HDDR phenomena.

Effect of Additive Elements in Cu of Co/Cu Multilayers on Magnetoresistance and Its Oscillation

We have investigated, experimentally, the effect of additive elements (X=Fe, Ni, Zn, Ru, Pd, Ag and Si) in Cu layers of Co/Cu multilayers on the giant magnetoresistance (MR) and its oscillation period (A) with respect to the Cu layer thickness. The change in MR is small for X=Fe, Ni, Zn, Pd and Ag, while a rapid decrease in MR is seen for X=Ru. These results are discussed in terms of spin-dependent scattering of electrons at interfaces. It has been found that A is enhanced by the addition of X=Fe, Ni and Pd.

Effect of Additional Elements on Glass Transition Behavior and Glass Formation Tendency of Zr–Al–Cu–Ni Alloys

The glass transition temperature (T g ) and crystallization temperature (T x ) of the Zr 65 Al 10 Cu 15 Ni 10 base glassy alloys containing additional M (M=Ti, Hf, V, Nb, Cr, Mo, Fe, Co, Pd or Ag) elements were examined as a function of M elements, with the aim of finding an effective element for the increase in ΔT x ( = T x - T g ) and of confirming the appropriateness of the previous empirical rules for the appearance of large ΔT x . As the additional amount of the M elements except Hf increases, T g increases gradually, whereas T x decreases significantly and leads to the decrease in ΔT x . No effective M element leading to the increase in ΔT x is found. The ineffectiveness is attributed to the partial generation of repulsive bonding nature of Cu-M (M=V, Nb, Cr, Mo, Fe, Co, Pd or Ag) and Zr-M (M=Ti of Hf) pairs which does not satisfy the empirical rules. The area ratio of the glassy region in the arc-melted ingots with a maximum thickness of about 8 mm was found to increase from 67% for the Zr-Al-Cu-Ni alloy to about 90% for the Zr-based alloys containing 5%Ti, 2.5%Nb or 5%Pd, though ΔT x decreases significantly by the addition of these elements. The great effectiveness of the three elements on the glass-formation tendency in the arc-melted ingots is interpreted to originate from the suppression of the growth reaction of crystalline nulcei which pre-exist in the arc-melted alloy. Furthermore, the disagreement between the glass-formation tendency evaluated by ΔT x and the area ratio of the glassy region is thought to result from the difference in the dominant factors which are the crystalline nucleation and growth reactions for the ΔT x of the melt-spun glassy alloys and the growth reaction for the area ratio of the glassy region in the arc-melted ingot. The finding of the additional elements leading to the increase in the glass-formation tendency of the arc-melted alloys, regardless of the magnitude of ΔT x , seems to be a very encouraging event for future development of bulk glassy alloys.

Effects of Additive Elements on Electrical Properties of Tantalum Oxide Films.

AbstractTa2O5-based composite films prepared by magnetron sputtering have been investigated with respect to their dielectric properties. As additive third oxides, Y2O3 and WO3 were found to be effective in improving insulating properties without decreasing their dielectric constant. Furthermore, electrical properties of Ta2O5-Y2O3 films were investigated by measuring the current-voltage characteristics in the temperature range from 100 to 330 K. Measurement of temperature dependence of the leakage current revealed that the conduction mechanism at RT changed from the Poole-Frenkel type to the Fowler-Nordheim tunneling type by adding Y2O3 into Ta2O5. Based on the detailed analysis of the results, it is concluded that the addition of Y2O3 into the Ta2O5 film is effective in the reduction of defect density without high-temperature annealing and the alteration of electrical conduction mechanisms of the films.

Effects of additive elements on electrical properties of tantalum oxide films

Ta2O5-based composite films prepared by magnetron sputtering have been investigated with respect to their dielectric properties. As additive third oxides, Y2O3 and WO3 were found to be effective materials for improving insulating properties. In these composite films, the dielectric constant remained unchanged. The maximum storage charge of the composite films was twice that of Ta2O5 films. The main reason for improving the insulating properties could be explained by the charge compensation of excess oxygen by these additive oxides.

Effects of additional elements on magnetic properties and grain size distribution of sintered iron-neodynium-boron alloys

Effects of additional elements on magnetic properties and grain size distribution of sintered iron-neodynium-boron alloys

Effect of additional elements on the thermal relaxation of magnetic anisotropy in amorphous TbCo films

The effect of additional elements on the thermal relaxation of magnetic anisotropy in amorphous TbCo films was studied. Tb-Co amorphous films with various additional elements were prepared, and their perpendicular anisotropy was measured after annealing. It was found that the addition of B or C is effective in suppressing thermal relaxation. By the addition of these elements the relaxation time for the magnetic anisotropy could be extended by a factor of 10. A simple model is proposed in which these light element atoms fill holes in an amorphous structure, thus suppressing changes in the atomic arrangement.

Effect of additional minor elements on microstructural evolution of neutron irradiated FeCrMn alloys

To study irradiation damage and the effects of additional elements on phase stability and void swelling, Fe10Cr15Mn and Fe10Cr15Mn3Al alloys were neutron irradiated in FFTF/MOTA at 365, 420, 520 and 600°C to 1 × 10 22/cm 2, 9.54 × 10 22/cm 2, 9.56 × 10 22/cm 2, and 9.6 × 10 22/cm 2, respectively. The structures of these alloys were observed by TEM and the compositional changes were analyzed using a 200 kV TEM with an EDX analyzer. The alloys contained austenite and ferrite phases. The fraction of ferrite in the alloy with Al was larger than for in the pure Fe10Cr15Mn alloy. Voids were formed at each irradiation temperatures in the austenite phase but not in the ferrite. In the F10Cr15Mn alloy the phase transformation from austenite to alpha martensite phases occurred at 365 to 420°C and at higher temperature the ferrite phase was newly nucleated from austenite matrix. Furthermore a chi phase with higher manganese was formed in the transformed alpha martensite but the occurrence of these new phases were not detected in the alloy with aluminum.

Effect of additional elements on the mechanical and microstructural properties of copper polycrystal under dynamic compression

The effect of additional elements (Si and Co) on the behavior of copper polycrystalline alloy under static and dynamic compression was studied. Relations between the deformation microstructure and the mechanical behavior have been investigated. In the Cu–Si alloys, the SFE depends on additional element content and the SFE level controls the dissociation of perfect dislocations into partial ones. In the Cu–Co alloy, Co induces precipitation and the dislocation repartition is uniform if the precipitates are coherent. When the precipitates become semicoherent, there is formation of dislocation walls around the precipitates.

Study on phase stability in TiAlX systems at high temperatures

The effect of additional elements X(XV, Cr, Mn, Nb, Mo and Ta) on γ(TiAl)-based titanium aluminides has been investigated. The addition of elements X caused a change in phase equilibria among the γ, α 2(Ti 3Al) and β (b.c.c. Ti) phases; the β phase is stabilized by the addition (except XTa), resulting in a drastic change in microstructures. The TiAlMo system has shown unique behavior; the β phase region protrudes toward the α phase region around 1200°C in the ternary phase diagram. The β phase contained in specimens quenched from high temperature has a long-range ordering structure that is different from the B2 structure. The chemical potentials of the β, α and γ phases may have close values around 1200°C and their phase stabilities are strongly influenced by processing or heat treatment.

The effect of additional elements on the magnetic properties of hot-rolled NdFeB alloys

The magnetic properties of hot-rolled Nd 16Fe bal.B 6M 1.5 (M = Cu, Ga and Al) and Nd 16Fe 76B 5.5Ga 1.5Al 1 alloys were investigated, in order to study the role of additive elements in improving the magnetic properties in the NdFeB system. It is found that the original grain size of Cu, Ga or GaAl added alloys is much finer than that of the ternary and Al added alloys. But the grain size is almost identical for all the alloys after hot-rolling at 1000°C with 90% reduction in thickness. The coercivity of hot-rolled alloys with Cu, Ga or GaAl addition is not improved as was expected, because Nd-rich liquid phase in these alloys is very easily squeezed out during high-reduction-ratio rolling. Less quantity and nonuniform distribution of Nd-rich phase between distributed grains are believed to be the main reasons to depress the effect on the grain boundary smoothing. This effect is not the same as those observed in the PrFeB system. The highest magnetic properties achieved in this study are B r = 10 kG, i H c = 8.2 kOe, ( BH) max = 18.5 MGOe for the Nd 16Fe 76.5B 6Al 1.5 alloy.

小特集 異種材料間の界面現象 ＡｌＮ／Ｃｕ間の反応層成長に対する合金添加元素の影響

小特集 異種材料間の界面現象 ＡｌＮ／Ｃｕ間の反応層成長に対する合金添加元素の影響

Effects of additional elements (IVa ∼ VI a) on thermal stability of Fe-C/Ni-Fe multilayers

Ion beam-sputtered Fe-2 at%C-M/Ni-20 at%Fe multilayers (M : Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) are heat-treated and the effects of additional elements on thermal stability are examined. The temperature at which coercivity increases abruptly due to the heat treatment rises by adding certain elements, i.e. Hf and Ta, and the thermal stability of the films is improved. The formation of γ-Fe in the films at high annealing temperatures decreases the saturation magnetic flux density of the films. However, the addition of elements, i.e. Hf and Ta, maintains the saturation magnetic flux density of the films even after heat treatment. The elements which improve the thermal stability of an Fe-C/Ni-Fe multilayer are those with a low free energy for forming carbides and little solubility in Fe, such as Hf, Zr, Ta and Nb.

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.

Effect of additional elements on cavity formation near grain boundary in proton-irradiated austenitic stainless steels

Using 140 keV H 2 + ion irradiation, the segregation of hydrogen along grain boundaries in type 304L, Ti- and Nb-modified austenitic stainless steels was studied. The irradiation was performed at temperatures up to 673 K and doses up to 3 × 10 21 H 2 +/m 2. Cavities formed along grain boundaries in type 304L after irradiation. The number density and diameter of the cavities were less in the Ti- and Nb-modified steels compared with that of 304L. It appears that Ti and Nb contribute to a decrease in the amount of hydrogen trapped along grain boundaries.

Effect of additional elements in Ag-Cu based filler metal on brazing of aluminum nitride to metals.

Brazing of aluminum nitride to copper was performed using Ag-Cu-Ti, Ag-Cu-Ti-Co and Ag-Cu-Ti-Nb brazing filler metals in an argon atmosphere. The reaction layer formed at the interface between AlN and braze layer in AlN-Cu joints was found to increase by increasing brazing time for all brazing filler metals used. In the case of the fillen metal Ag-Cu-Ti-Nb, a thinner reaction layer was formed in comparison with the cases of using other filler metals. Form an EPMA analysis, it was found that not only Ti, but also Nb were concentrated in this thin reaction layer. From XRD analysis, it was found that TiN lattice was distorted by Nb addition. Shear strengths were measured for AlN-W joints at room temperature. The joint brazed at 1 173 K for 0.3 ks using Ag-Cu-Ti filler metal showed a strength of 118 MPa. In the case of using Ag-Cu-Ti-Co filler metal, almost the same shear strength, 116 MPa, was obtained after brazing at 1 173 K for 0.6 ks. The joints brazed at 1 173 K for 0.3 ks using Ag-Cu-Ti-Nb filler metal exhibited the maximum shear strength 147 MPa. The shear strength of the joints was discussed in relation to the thickness of the reaction layer.

Effects of additive elements on continuous ultra-fine Nb/sub 3/Al MF superconductor

Nb/sub 3/Al multifilamentary (MF) wire can be fabricated by the composite process using various Al-based alloy cores and pure Nb matrix. Additive elements of Mg, Ag, Cu and Zn harden the Al core preferentially and then improve the workability of the Nb/Al composite, permitting it to be cold-drawn into a wire with ultrafine Al-based alloy filaments (filament number: 1.8 million, diameter: about 0.1 mu m). Reacted wires at 700-900 degrees C show T/sub c/ of 15-16 K, mu /sub 0/H/sub c2/ (4.2 K) of 21-22 T and J/sub c/ (4.2 K, 10 T) of 1-1.5*10/sup 9/ A/m/sup 2/. A two-stage reaction consisting of a reaction above 950 degrees C and a subsequent reaction around 700 degrees C is carried out to improve critical values; T/sub c/ and mu /sub 0/H/sub c2/ are increased to 17.4 K and 25.4 T, respectively. Excellent superconducting properties involving good strain tolerance ( epsilon /sub irrev/=1.3%) indicate that this Nb/sub 3/Al is very promising for practical high-field superconducting cables. >

アーク溶接過程における鋼溶接金属の酸素吸収におよぼす合金元素の影響 Ｉ Ｆｅ‐Ｓｉ溶接金属の酸素吸収について

アーク溶接過程における鋼溶接金属の酸素吸収におよぼす合金元素の影響 Ｉ Ｆｅ‐Ｓｉ溶接金属の酸素吸収について

Effects of Additional Elements on the Superplasticity of a Cu–14Al–3Ni Shape Memory Alloy

Effects of Additional Elements on the Superplasticity of a Cu–14Al–3Ni Shape Memory Alloy