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1.
In order to improve the tensile ductility of amorphous Fe 78Si 9B 13 alloy, nano-Ni layers were electrodeposited on the amorphous alloy ribbon and amorphous Fe 78Si 9B 13/nano-Ni laminated composite was prepared. The tensile ductility of laminated composite and monolithic amorphous alloy at both room and high temperatures was examined. The elongation of the amorphous Fe 78Si 9B 13 alloy and that in the laminated composite increases from 1.4% to 8.5% and from 36.3% to 115.5% at room temperature and 450 °C, respectively. The improved tensile ductility using electrodeposited nano-Ni layers is attributed to a good bonding between the amorphous Fe 78Si 9B 13 layer and nano-Ni layers. The amorphous layer can deform in conformity with Ni layers and be significantly stretched without fracture. 相似文献
2.
Formation and magnetic properties of the bulk amorphous Fe 60Co 10Ni 10Zr 7B 13 alloy are described. The amorphous powder was prepared by high-energy ball milling of the amorphous ribbon and then was pressed under high pressure and temperature to obtain a bulk alloy in the form of a disc 5 mm in diameter and 2.5 mm thick. The compacted discs are fully amorphous as confirmed by X-ray diffraction and Mössbauer spectroscopy measurements. Differential scanning calorimetry curve recorded for the amorphous ribbon shows two exothermal peaks related to two stages of crystallization. Similar thermal behavior is observed for the powder samples. Hysteresis loops obtained for the amorphous ribbon, as-milled and compacted powders reveal their soft magnetic properties. 相似文献
3.
The short-range order structures in ternary ZrF 4---BaF 2---ErF 3 glasses have been studied by X-ray absorption fine structure (XAFS). The near-neighbor structures around Zr, Ba and Er have been determined and compared with that in binary ZrF 4---BaF 2 glasses. The near-neighbor structures around Zr and Ba are scarcely affected by doping with ErF 3. The structural parameters of near neighbors around Er in the glasses are near to that in ErF 3, but the corresponding distance and coordination number of near neighbors in the glasses decrease slightly. It is also observed that the intensities of the white lines at the Er L and L absorption edges in these glasses are different from that in c-ErF 3. Meanwhile, compared with that of the corresponding fluoride, the changes of the ‘white line’ at the Er L ,-edges in the glasses differ from the case of Nd. The causes leading to these differences are discussed. 相似文献
4.
We have measured the temperature dependence of the internal friction and shear modulus of metallic glass alloys Fe 40Ni 40P 14B 6, Fe 29Ni 49P 14B 6Si 2, Fe 80B 20 and Fe 78Mo 2B 20 in the glassy and crystalline phases using a torsional pendulum technique. The internal friction in the glassy phase remains approximately constant from room temperature to a temperature which depends on the annealing treatment, and the rises exponentially with temperature. The internal friction measurements were made at two different frequencies (0.2 Hz and 1.0 Hz) and the activation energies for the relaxation processes estimated by the frequency shift method. The shear modulus increases by about 30% when the amorphous alloys are crystallized. The amorphous alloys Fe 80B 20 and Fe 78Mo 2B 20 exhibit Invar type behaviour which disappears upon crystallization. 相似文献
5.
Nickel-incorporated FeS 2 single crystals with various Ni compositions of Fe 0.99S 2:Ni 0.01, Fe 0.98S 2:Ni 0.02, Fe 0.96S 2:Ni 0.04, and Fe 0.9S 2:Ni 0.1 were grown by chemical vapor transport (CVT) method using ICl 3 as a transport agent. Physical properties of the Ni-incorporated FeS 2 single crystals were characterized using X-ray diffraction, Raman spectroscopy, electrical conductivity, and photoconductivity (PC) measurements. By means of the analyses of the X-ray diffraction patterns, the whole series of Ni-doped FeS 2 single crystals were determined to be single-phase and isostructural. Raman spectroscopy of the Ni-doped FeS 2 crystals was carried out at room temperature. Raman resonant peaks of the Ni-doped FeS 2 crystals demonstrate an energy red-shift behavior with respect to the increase of the dopant densities. Conductivity measurements show the resistivity of the Ni-doped FeS 2 decreased as the doping concentration of Ni is increased. Nickel is an n-type dopant, which behaves like a donor level existed near the conduction band edge of the synthetic FeS 2. On the other hand, dopant effect of nickel on the synthetic FeS 2 also destroys the photoconductive sensitivity in the photoconductivity measurements. 相似文献
6.
The changes in the atomic structure of amorphous Fe 40Ni 38Mo 4B 18 during the crystallization process were studied by X-ray diffraction. The radial distribution functions of various specimens frozen at significant points of the relative DSC thermograms, were obtained from the interference functions by means of the usual Fourier analysis. It appears from the results that the onset of crystal formation implies the simultaneous occurrence of atomic rearrangements involving the basic structural units already present in the unannealed sample; a five-fold symmetry and icosahedral structure were found for these units. An effort was made to correlate the progress in the crystalline organization with the significant features of the DSC related thermograms. 相似文献
7.
Ceramic materials with a very low thermal expansion coefficient are synthesized by the sol-gel process. The binary gel is obtained by hydrolysis and polycondensation reactions of organometallic compounds of aluminium and titanium. The thermal evolution of the amorphous powder is followed by DTA and TGA measurements. Structural evolution is followed using X-ray diffraction. The crystallization of the TiO 2 rutile and Al 2O 3 corindon starts at 700 and 900°C respectively. The transformation of Al 2O 3 and TiO 2 into Al 2TiO 5 appears between 1200 and 1300°C. The densification of the powder is performed by the hot pressing process. The shrinkage of the powder was previously followed by dilatometric measurements. The physical properties of the final material are studied as a function of pressing parameters. 相似文献
8.
X-ray crystallography and Mössbauer spectroscopy were used to investigate the crystallization of the amorphous Fe 100−xB x alloys, 14 x 20 annealed at 615 K. As a result of the heat treatment, the formation of crystalline -Fe and Fe 3B were observed. Variations in the values of the isomer shift and the orientation of the axis of magnetization indicate changes in the iron-boron bonding and the local atomic arrangement. Formation of the -Fe phase was determined as a function of boron concentration and annealing time. Crystallization rates of that phase were observed to be dependent on boron concentration and on the annealing time. The average hyperfine field of the untreated samples was observed to increase till x = 17 after which it decreased. This is explained in terms of the Invar behavior of Fe83B17. The anomalous crystallization of Fe86B14 is proposed to be due to the existence of interstitial-like boron sites in a near bcc short range atomic structure. 相似文献
9.
The electrical and dielectric properties for three series of MoO 3–Fe 2O 3–P 2O 5 and one series of SrO–Fe 2O 3–P 2O 5 glasses were measured by impedance spectroscopy in the frequency range from 0.01 Hz to 3 MHz and over the temperature range from 303 to 473 K. It was shown in Part I that the MoO 3 is incorporated into phosphate network and the structure/properties are strongly influenced by the overall O/P ratio. The Fe 2O 3 content and Fe(II)/Fe tot ratio in these glasses have significant effects on the electrical conductivity and dielectric permittivity. With decreasing Fe 2O 3 content in MoO 3–Fe 2O 3–P 2O 5 glasses with O/P at 3.5 the dc conductivity, σ dc(ω) decreases for two orders of magnitude, which indicates that the conductivity for these glasses depends on Fe 2O 3 and is independent of the MoO 3 content. Also, the dielectric properties such as ′(ω), ″(ω) and σ ac(ω) and their variation with frequency and temperature indicates a decrease in relaxation intensity with increase in the concentration of MoO 3. On the other hand, the dc conductivity for MoO 3–Fe 2O 3–P 2O 5 glasses with O/P > 3.5 increases with the substitution of MoO 3 which has been explained by an increase in the number of non-bridging oxygens and formation of Fe–O–P bonds that are responsible for formation of small polarons. The increase in the dielectric permittivity, ′(ω) with increasing MoO 3 content is attributed to the increase in the deformation of glass network with increasing bonding defects. For SrO–Fe 2O 3–P 2O 5 glasses the conductivity and dielectric permittivity remained constant with increasing SrO. 相似文献
10.
The extensional sound velocities VE of Fe 80−xMo xB 20( x = 6, 7, 8) metallic glasses have been measured between 100 and 600 K in a saturating magnetic field. Young's modulus ( E = E2, = density) shows anomalous temperature dependence at and below the magnetic transition temperature of each glass studied. These anomalies are interpreted as arising from the change of long-range spin coupling energy at the Curie temperature in a molecular field approximation. Comparison is made with similar effects in other crystalline and non-crystalline magnetic materials. 相似文献
11.
Mössbauer absorption measurements have been made at room temperature on 57Fe in iron sodium silicate glasses containing 3–15 mol% Fe 2O 3 and various iron alkali silicate crystals in order to study the state of iron in these glasses. The spectra of all the glasses gave one doublet with a quadrupole splitting varying from 0.73–0.78 mm s −1, while those of Na 2O · Fe 2O 3 · 4 SiO 2 and 5 Na 2O · Fe 2O 3 · 8 SiO 2 crystals showed much smaller quadrupole splitting, 0.28 mm s −1 and 0.10 mm s −1, respectively, and an asymmetrical doublet of much narrower linewidth. When sodium was replaced by other alkali metals of larger size, such as K and Cs, in MFeSi 2O 6 and MFeSi 3O 8 crystals, the quadrupole splitting became wider and approached to 0.73 mm s −1. Such a variation was not observed for glasses. These results suggest that a larger number of non-identical sites exist in iron sodium silicate glasses than in the corresponding crystals. 相似文献
12.
The surface structure of partially crystallized Fe 78Si 12B 10 alloys was investigated by means of X-ray diffraction, high resolution electron microscopy and Auger electron spectroscopy and was correlated with their catalytic properties. Highly dispersed minute -Fe particles were observed in the amorphous matrix. After chemical treatment of the partially crystallized Fe---Si---B alloys with NaOH solution, large stripes of B 2O 3 were discovered because of the aggregation of a boron-containing phase. Boron- or silicon-containing surface films were formed on the -Fe particles by diffusion, causing the deactivation of these alloy catalysts. 相似文献
13.
A novel process for producing amorphous state, namely photo-induced transformation, is reported in a chalcogenide material, As 50Se 50, which in the crystalline phase is a molecular solid consisting of As 4Se 4 molecules. The crystalline-amorphous transition is athermal. Although the mechanism of photo-induced transformation to the amorphous state is not known, two possibilities are suggested: either photon-induced intramolecular bond-breaking leading to a cross-linked CRN-like network, or intermolecular bond-breaking resulting in an orientationally disordered molecular glass. 相似文献
14.
Both conventional thermal treatments (CTTs) and nitriding thermochemical treatments (NTTs) are used to crystallize Fe 74Si 14B 12 and Fe 73.5Si 13.5B 9Cu 1Nb 3 melt spun ribbons. For the FeSiB sample, nitrogen is detected throughout the whole thickness, while nitrogen is observed only in the periphery of the (Cu–Nb) containing sample. Nitrogen diffusion is related to the crystallization. The remaining phase in the nanocrystallized FeSiBCuNb sample slows down the nitrogen diffusion. This kind of treatment applicated to FeSiBCuNb sample enables the formation of nanocrystallites with a grain size that is slightly smaller than that obtained following a CTT. 相似文献
15.
Dynamic mechanical properties of an amorphous La 55Al 25Ni 20 alloy were measured by a forced oscillation method in the temperature range from room temperature to 453 K, just below the glass transition temperature ( Tg = 481 K). The internal friction at a constant frequency 62.8 rad/s of this alloy showed a peak at about 400 K and the peak position shifts with frequency. Structural relaxation reduces the magnitude of the relaxation peak but has little affect on the peak position. Using the time-temperature superposition process, master curves for storage E′ (ln ω) and loss E″ (ln ω) moduli are constructed. Activation energy of the relaxation obtained from shift factors is low, 100 kJ/mol, which is close to that for diffusion of the Al in Al and Ni in Al. The relaxation spectra are very broad with a half width of 2 3 decades. 相似文献
16.
The influence of dilute concentrations (<10 at.%) of Pt-group metals (Re, Ru, Os, Ir, Pd and Pt) on the thermal-stability of melt-spun (Fe or Ni) Si 10B 12-based amorphous alloys has been investigated by differential scanning calorimetry. The stability of the Fe-based alloys, with the exception of those containing Pd or Pt, can be related to both the electronic and atomic-size differences between solvent and solute metal species, as we observed previously for other solutes from groups IVa–VIa. Addition of Ru, Pd or Pt to glassy NiSi 10B 12 has little effect on the stability, and no correlation with atomic size or electron concentration could be established. 相似文献
17.
A novel compound with the chemical formula of La 2SrB 10O 19 has been successfully synthesized from the La 2O 3--- SrO---B 2O 3 system via a solid state reaction. The powder X-ray diffraction data is reported. It is found that the data show little difference from that of La 2CaB 10O 19 which demonstrate that they are isostructural. The powder second harmonic generation effect of La 2SrB 1)O 19 is about twice that of KH 2PO 4(KDP). The investigation of crystal growth is in progress. 相似文献
18.
The enthalpy relaxation behaviour of metal-metalloid type (Fe 0.5Co 50.5) 83P17 and metal-metal type (Fe 0.5Co 0.5) 90-Zr10 amorphous alloys was investigated with a DSC measurement. The annealing temperature ( Ta) dependence of the annealing-induced reversible enthalpy relaxation evaluated with an endothermic showed the maximum at thesame Ta for the two alloys, but the magnitude of the relaxation was considerably smaller for the (Fe 0.5Co 0.5) 90Zr 10 alloy. Moreover, it was found that the amorphous (Fe 0.5Co 0.5) 90Zr 10 alloy has a larger atomic packing density and a higher activation energy of the enthalpy relaxation than the amorphous (Fe 0.5Co 0.5) 83P 17 alloy. Rhe small enthalpy relaxation and high activation energy for the amorphous (Fe 0.5Co 0.5) 90Zr 10 alloy were ascribed to the highly packed structure of the metal-metal type amorphous alloy. 相似文献
19.
In amorphous (a-) GeS 2 there is only one medium-range order (MRO) dependent X-ray scattering feature, i.e., the ‘first sharp diffraction peak’ (FSDP), whereas in a-Sb 2S 3 all scattering features in the interval 1–2.4 Å −1 are in fact MRO-dependent. The basic element of MRO in a-GeS 2 is a part of a chain of corner bound tetrahedra extracted from the high temperature form of c-GeS 2; in a-Sb 2S 3 it is a part of a crystalline-like (Sb 2S 3) n band. Ordering of parts of these bands is characterized by a greater interband separation than in the crystal. By contrast with a-GeS 2, the MRO-dependent medium-angle scattering features in a-Sb 2S 3 are less sensitive to fluctuations of the interband (intercluster) ordering distance. 相似文献
20.
Photoluminescence (PL) originating from intrinsic defects in neutron-irradiated crystalline (x-) SiO 2 is observed and compared with that from amorphous (a-) SiO 2. The PL and photoluminescence excitation (PLE) spectra of x-SiO 2 are qualitatively similar to those of a-SiO 2. This suggests that PL centers, similar to those found in amorphous systems, are present in ordered systems. In addition, the PL and PLE spectra a-SiO 2 and a-As 2S 3 scale with energy band gap, suggesting that the radiative processes in a-SiO 2 and semiconducting chalcogenide glasses are alike. The similarity of the PL from x-SiO 2 to that from a-SiO 2 and the scaling of the PL from a-SiO 2 and a-As 2S 3 with energy band gap strongly suggest that PL centers are unique bonding configurations which primarily depend on the chemistry of the system rather than on the degree of long range order. 相似文献
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