Magnetic clusters in amorphous Fe90Sc10 alloy

In order to obtain information on the nature of spin coupling in Fe-rich alloys, we performed high-precision⁵⁷Fe Mössbauer effect and magnetizations measurements in a wide temperature range. These results show that with increasing temperature amorphous Fe₉₀Sc₁₀ alloys undergo a transition from a cluster spin-glass to superparamagnetism followed by paramagnetism.     

Mössbauer study on surface crystallization behavior of amorphous Fe90Zr10 alloy ribbon

The precipitous drop of crystallization temperature at the surface of amorphous Fe₉₀Zr₁₀ ribbon is confirmed by TMS and CEMS. The deficiency in Zr at the surface amorphous phase, caused by the absorption and the diffusion of oxygen, is found to be responsible for it. The final crystalline products are assigned to α-Fe, Fe₃Zr and Fe₂Zr, whereas only α-Fe precipitates at the surfaces. Moreover, it is indicated that the crystallization behavior of the bulk is influenced by the ambient gases during annealing and quite different between in vacuum and in air.     

Evaluation of the iron hyperfine field distribution in amorphous Fe90Zr10

The separated 2–5 lines of the Mössbauer spectrum of amorphous Fe₉₀Zr₁₀ alloys has been obtained from the linear combination of the spectra of unpolarized and magnetically polarized samples. The hyperfine field distribution has been determined from the original spectra and from the separated 2–5 lines using different evaluation methods (binomial distribution method. Fourier method and Window method).     

Phase segregation and crystallization in the amorphous alloy Ni70Mo10P20

Structural evolution of the amorphous alloy Ni₇₀Mo₁₀P₂₀ has been studied by x-ray diffraction, and by following transmission and high-resolution electron microscopy annealing both above and below the glass-transition temperature. When annealed above this temperature, the amorphous phase undergoes segregation into regions about 100 nm in size having different chemical composition. Diffraction from such samples produces diffuse rings, and the scattering vector corresponding to the maximum intensity varies from point to point within the interval of 4.88 to 4.78 nm⁻¹. When occurring between the glass-transition and crystallization temperatures, crystallization produces groups of nanocrystals, 20–30 nm in size, which are in direct contact with one another and form a polymorphic mechanism. The crystallization mechanism changes when the annealing temperature is brought below the glass-transition point. At these temperatures the amorphous matrix crystallizes entectically with formation of eutectic colonies. Fiz. Tverd. Tela (St. Petersburg) 40, 1577–1580 (September 1998)     

Crystallization of the amorphous Fe45Ni35Si10B10 alloy due to pulse heating

The effect of rapid heating on the stability of amorphous Fe₄₅Ni₃₅Si₁₀B₁₀ is studied in detail by Mössbauer spectroscopy. Structural relaxation as well as formation of crystalline α-Fe and γ(FeNi) is observed, depending on the heating and cooling conditions applied.     

Variation of magnetic state of amorphous Fe90Zr10 and Fe91Hf9 by the charge of hydrogen

Amorphous Fe₉₀Zr₁₀ and Fe₉₁Hf₉ ribbons were charged with hydrogen by the electrochemical method up to Fe₉₀Zr₁₀H₂₆ and Fe₉₁Hf₉H₁₅, respectively, and the change in magnetic structures were analyzed by Mössbauer spectrometry. The internal magnetic field appeared by the charge of hydrogen, the degree of change being depended on amounts of hydrogen included in amorphous Fe₉₀Zr₁₀ and Fe₉₁Hf₉, although Fe₉₁Hf₉ absorbed hydrogen more slowly than Fe₉₀Zr₁₀. The differences of hydrogen inclusion and Mössbauer hyperfine structure between Fe₉₀Zr₁₀ and Fe₉₁Hf₉ were discussed based on the results of a hyperfine field distribution and the radial distribution functions of Fe?Fe obtained by EXAFS.     

Mössbauer study and magnetic moments of Fe90−xCoxZr10 and Fe90−xNixZr10 amorphous alloys

The⁵⁷Fe Mössbauer spectroscopy of amorphous Fe_90–xCo_xZr₁₀ and Fe_90–xNi_xZr₁₀ provided strong evidence for the unusual large enhancement of the Fe magnetic moment in these alloys.     

Phase transformations of the amorphous Zn-Sb alloy under high pressures

Abstract

Phase transformations occurring in initially amorphous Zn₄₁ Sb₅₉ semiconductor at pressures to 10 GPa and temperatures to 350C were studied using the measurement of electrical resistance, in situ energy dispersive X-ray diffraction and neutron diffraction on quenched high-pressure phases at ambient pressure. The studied T- P region involves the regions of reversible and irreversible crystallisation and phase transitions between the equilibrium crystalline low-pressure and high-pressure phases.     

Nanocrystallisation of an Fe44.5Co44.5Zr7B4 amorphous magnetic alloy

The crystallisation of amorphous Fe_44.5Co_44.5Zr₇B₄ was investigated using DSC, electrical resistivity, TEM, HRTEM, CBED and VSM. Melt-spun amorphous Fe_44.5Co_44.5Zr₇B₄ crystallised by the primary crystallisation mode: the DSC results showed two exothermal peaks during heating. The electrical resistivity dropped sharply during the crystallisation event, which was consistent with DSC characterisation. From TEM, HRTEM and CBED results, primary crystallisation products which appeared to be clusters of crystals were found to be single crystal precipitates; these crystals formed in a compact dendritic morphology. Direct measurement of nucleation density and volume fraction was carried out using TEM analysis. The nucleation density was found to be high even in the absence of copper addition. The crystal growth was slow when the average size reached around 30?nm; this resulted in a stable nanocrystalline structure. The soft magnetic properties were improved after nanocrystallisation, the magnetic properties were related to the crystalline volume fraction and the Herzer model.     

Mössbauer study of the crystallization products of a Fe75Zr25 amorphous alloy

The crystallization of the Fe₇₅Zr₂₅ as-milled amorphous alloy has been studied by Mössbauer spectroscopy. The process begins at around 880 K with the complete and fast crystallization of the amorphous phase into the crystalline α-Fe and Fe₂Zr ones but, from around 915 K, there is a sudden phase transformation into the Fe₂₃Zr₆ phase, which remains stable after cooling. A fitting for the Mössbauer contribution of the Fe₂₃Zr₆ phase, consistent with its crystalline structural features, has been obtained.     

Effect of mechanical tension on electrical transport properties of amorphous Fe92Zr8 alloy

The effect of mechanical tension and magnetic field on the electrical resistivity of amorphous Fe₉₂Zr₈ alloy has been studied as a function of temperature. The results show that resistivity is enhanced by the applied tension and magnetic field. The increase in the electrical resistivity is attributed to volumetric effect, disorder scattering and thermal vibrations. The observed increase in the Curie temperature caused by the applied stress was found to be about 7×10^–6 °C/PA and indicates that some structural changes occurred.     

块体非晶合金 Zr55Cu30Al10Ni5 结构弛豫的研究

应用同步辐射小角x射线散射和差示扫描量热分析对块体非晶合金Zr55Cu30Al10Ni5结构弛豫进行了研究.实验结果表明:经340℃、不同时间退火后的非晶内部的电子密度涨落随退火时间的延长先增大而后减小;玻璃转变温度附近焓弛豫峰的表观激活能则随退火时间的延长先减小而后增大.结果反映了随退火时间的延长,块体非晶合金内部类液体区不断减少及类固体区不断增加的过程.     

Cu60Zr30Ti10非晶合金弛豫和晶化过程的小角X射线散射研究

应用小角X射线散射技术研究了Cu60Zr30Ti10非晶合金从300到813 K之间微结构的演化情况.发现在淬火状态下Cu60Zr30Ti10非晶合金中存在直径30 nm左右的富Cu区.非晶的结构弛豫包括573 K之前的低温结构弛豫和573 K到玻璃转变温度的高温结构弛豫,弛豫的结果是产生含有有序原子团簇的富Cu区,这些有序原子团簇的富Cu区是随后晶化过程中晶核产生的基础.Porod曲线分析表明,晶化生成的纳米体心立方CuZr相和基体之间有明锐的界面.     

Magnetic properties of the amorphous alloy Fe80Er20

Amorphous Fe₈₀Er₂₀ alloys were prepared with the melt spinning technique. The ribbons were investigated by Mössbauer spectroscopy from room temperature to 4.2 K. A phase transition from the paramagnetic to the ferromagnetic phase could be observed. The temperature dependence of the internal magnetic field was measured. The correlations of the hyperfine parameters were determined from the 4.2 K spectrum.     

Structural segregation in amorphous Fe40Ni40P14B6 under heat treatment and natural ageing

Transmission and depth selective conversion electron Mössbauer spectroscopy (DCEMS) were applied usefully to study structural transformation in the bulk and in the surface layer in a≈50 and 100 nm thick amorphous alloy that was subjected to annealing and natural ageing. Analysis of the hyperfine field distributionsP(H) shows the segregation of the amorphous matrix.