Development of microstructure in advanced solidification processing

This paper gives an overview of the use of process monitoring measurements, computer modelling calculations and electron microscope material characterization techniques to understand and control the manufacture of materials by a variety of advanced solidification processing methods. Examples which are discussed include: (1) spray formed Al alloys and composites for aerospace structures; (2) squeeze cast Al alloys and composites for automotive components; (3) melt spun Al bearing alloys and; (4) melt spun amorphous Fe alloys for distribution transformer cores and structural components; and (5) plasma sprayed Ti composites for aeroengine compressors.     

稀土元素钐的光电流光谱

利用光电流信号研究了稀土素钐的原子光谱。钐原子被染科激光（由氩离子激光泵浦若丹明６Ｇ）激发。实验中探测了从６０８．０００－６２１．０００ｎｍ的大约２０条谱线，对其中大部分谱线作了指认，发现了一些新谱线。对钐原子中光电流信号的正，负特性作了讨论。     

Assessment of thermal-treatment conditions for age-hardenable particulate-reinforced aluminium alloys by calorimetric methods

To assess the influence of ceramic reinforcements on the solid-state transformations that proceed during processing, fabrication and application of particulate-reinforced age-hardenable aluminium alloys (PRA), microcalorimetry and differential scanning calorimetry investigations were carried out in combination with microstructural and mechanical investigations. PRA-material studies were conducted on the AlCuMg (2014), AlMgSi (6061, 6082) and AlZnMgCu (7075) alloy systems containing Al₂O₃-and SiC-particulates with volume fractions between 10-25%. In order to cover the whole range of PRA-production and application, the consequences of the presence of ceramic particulates were investigated with respect to high-temperature exposures (homogenisation, extrusion, solution treatment), to cooling rates from solution treatment and to precipitation strengthening by natural and/or artificial ageing. The various effects are highlighted for selected PRA-systems and PRA-conditions, and the overall mechanisms are discussed. Implications for modifications of processing and fabrication parameters in order to optimally exploit the potential of PRA-material are discussed.     

ICP－AES法测定铂催化网中的次成分及杂质元素

本文采用ＩＣＰ－ＡＥＳ内标法，对硝酸生产用铂催化剂的次成分Ｐｄ和Ｒｈ，以及十一个杂质元素，进行直接快速测定。部分受干扰的元素，采用扣除其相应等效强度的方法进行校正。本方法的回收率和相对标准偏差，对于次成分分别为：９９．１～１００％和０．１６～０．３１％；对于杂质元素分别为：９５～１１４％和０．８３～１３％。     

Alloys prepared by plasma-enhanced chemical vapor deposition (PECVD)

Three different techniques for the deposition of thin metal alloy films by plasma-enhanced chemical vapor deposition are described. These are the joint vaporization of a mixture of precursors, the use of separate sources connected directly to the reactor, and finally, the use of several reservoirs arranged in series. Various organometallics have been used as precursors to prepare combinations of Fe/Co and Au/Pt/Pd.     

Synthesis and electrophysical properties of novel lithium ion conducting oxides

Novel lithium ion conducting oxides with perovskite structure have been synthesized and studied. It has been found that the La_2/3−xLi_3xTiO₃ and La_2/3−xLi_3xNb₂O₆ compounds have a perovskite structure at 1/24 < x < 1/6 and 0 < x < 3/10, respectively. The results of investigating the electrical properties of both groups of perovskites indicate a high lithium ion conductivity.     

Fractal study of Ni–Cr–Mo alloy for dental applications: effect of beryllium

Different Ni-based alloys with various compositions were prepared by varying the amounts of beryllium. Effect of the amount of beryllium added to the alloy on its corrosion in an electrolyte solution of artificial saliva was investigated. Fractal dimension was used as a quantitative factor for surface analysis of the alloys before and after storage in the artificial salvia. The fractal dimensions of the electrode surfaces were determined by means of the most reliable method in this context viz. time dependency of the diffusion-limited current for a system involving “diffusion towards electrode surface”. The results showed that increase of the beryllium amount in the alloy composition significantly increases the alloy corrosion. It is accompanied by increase of the fractal dimension and roughness of the electrode surface, whereas a smooth and shiny surface is required for dentures. From the methodology point of view, the approach utilized for fractal analysis of the alloy surfaces (Au-masking of metallic surfaces) is a novel and efficient method for study of denture surfaces. Generally, this approach is of interest for corrosion studies of different metals and alloys, particularly where changes in surface structure have a significant importance.     

Monte Carlo study of the magnetic properties of Fe0.9−qMn0.1Alq-disordered alloys

Within the framework of a random site-diluted Ising model with nearest-neighbor interactions, and using the Metropolis algorithm for equilibration and energy minimization, we have computed the ensemble and configurational averages for magnetization per site, magnetic susceptibility and specific heat of Fe_0.9−qMn_0.1Al_q-disordered alloys with 0.1q0.55. In the model, atoms have been randomly distributed on a body-centered cubic lattice in order to simulate the disorder and structure as that obtained in arc-melted Fe_0.9−qMn_0.1Al_q alloys treated at high temperatures during long periods of time and followed by fast quenching. Competitive interactions coming from Fe–Fe ferromagnetic bonds and Fe–Mn and Mn–Mn antiferromagnetic couplings, as well as the Al dilutor effect, have been taken into account in our study. Results allow us to conclude that, in agreement with previous Mössbauer data of the average hyperfine field, for which a comparison is also carried out, the Fe_0.9−qMn_0.1Al_q-disordered alloys are well characterized by a critical concentration at room temperature at around 40 at% Al, for which the system undergoes a transition from a ferromagnetic state to a paramagnetic one. The finite size scaling analysis to obtain the critical Al concentration in the thermodynamic limit, as well as the critical exponents, is also presented and discussed.     

Structural phase transition in FeBO under pressure

Using the density functional theory the structural and magnetic properties of iron borate under high pressure have been studied. At about P = 22.7 GPa a first order phase transition to the phase described by the same space group Rc has been found. The phase transition is accompanied by a 9% volume change of the unit cell, a four times decrease of the magnetic moment on Fe, an increase of the charge density at Fe, and a disappearance of the energy gap in the electronic density of states. Received 21 September 2001 and Received in final form 6 January 2002 Published online 6 June 2002     

高压下Zr70Cu30非晶合金的热稳定性和晶化相的变化

 用电阻测量及X射线衍射法研究了非晶Zr₇₀Cu₃₀合金在常压和高压下热稳定性以及晶化相的变化。结果表明压力提高了这种非晶合金的晶化温度并明显地改变了合金中的相平衡关系。在2 GPa压力下，平衡相为Cu₁₀Zr₇和α-Zr的混合物，而常压下为CuZr₂和少量α-Zr的混合物。