Reaction laser sintering of Ni–Al powder alloys

Laser reactive sintering, i.e., laser-induced self-propagating reaction sintering synthesis was carried out on Ni–Al powder alloys. The exothermic behaviors for the alloys with different Al content were characterized by sintering temperature curves produced from reactive heat. The phases transformed from the sintered alloys were identified by X-ray diffraction. Properties and microstructure of the sintered alloys were studied.     

Structural evolution of FexCo1−x/NM (NM=Ag, Cu, Al2O3) discontinuous multilayers by XAS

We discuss the specific features of the K-edge X-ray absorption spectroscopy (XAS) at the Fe and Co K-edges in Fe_xCo_1−x/NM discontinuous multilayers with NM=Ag, Cu, and Al₂O₃. Thermal treatments lead to the breakup of the layers forming a heterogeneous alloy with magnetic clusters of the FeCo embedded in a nonmagnetic (NM) matrix. Stabilization of the BCC phase of the FeCo alloy is directly evidenced by XAS. Differences among Fe and Co K-edge signatures indicate a strong dependence on the chemical nature of the absorbing atom for annealed samples. The amplitude of the extended X-ray absorption fine structure signal higher at the Co K-edge than at the Fe one reflect a smaller structural disorder in the Co environment. This behavior depends neither on the composition of the alloy nor on the NM material. In the case of Al₂O₃ a higher disorder around Fe atoms is observed also in the as-deposited sample. All these results indicate that the Fe segregates at the interface of the magnetic clusters/NM matrix after thermal annealing.     

A constitutive relation for pseudo-elastic behaviour in shape memory alloys

A constitutive relation to describe pseudo-elastic deformation in shape memory alloys is presented in this paper. It is capable of describing deformation behaviour of polycrystalline materials under triaxial stress state as well as of monocrystalline materials under one-dimensional condition. Total strain rate is supposed to be composed of elastic strain rate and transformation strain rate. Deformation behaviour of Cu−Zn−Sn alloy and Ti−ni alloy is simulated by use of the proposed constitutive relation. it is shown that simulated results are in a good agreement with experimental data. The project supported by National Natural Science Foundation of China.     

Evolution of magnetic, structural and mechanical properties in FeSiBNbCuAlGe system

The influence on mechanical and magnetic properties of adding different proportions of Ge and Al to the well-known FeSiBNbCu system is analyzed in ribbons obtained by the melt-spinning technique and heat treated at several temperatures. These results and the changes observed in the internal structure are compared with those obtained in similar studies performed on the Fe_73.5Si_22.5−xB_xNb₃Cu₁ alloy.     

Atomic displacements in dilute alloys of Cr, Nb and Mo

Kanzaki lattice static method is used to calculate the atomic displacements due to substitutional impurities in 3d (Cr) and 4d (Nb, Mo) metals. Wills and Harrison interatomic potential is used to calculate dynamical matrix and the impurity-induced forces up to second nearest neighbors. The calculated atomic displacements for 3d, 4d and 5d impurities in Cr (V, Mn, Fe, Ni, Nb, Mo, Ta and W), Nb (V, Cr, Mn, Fe, Zr, Mo, Ta and W) and Mo (V, Cr, Mn, Fe, Zr, Nb, Ta and W) are tabulated up to 10 NN’s. The strain field due to 3d impurities is least in Cr metal while it is larger in Nb and Mo metals. For 4d and 5d impurities the strain is larger in Cr metal than in Nb and Mo hosts. Similar trend is found for relaxation energies also.     

Electronic structure of Sr2FeMoO6

We have used electron spectroscopies to investigate the electronic structure of the double perovskite Sr₂FeMoO₆. The valence-band photoemission spectra present a well-defined cut-off at the Fermi level, indicative of the metallic character of the material. The O 1s X-ray absorption spectrum presents three peaks, which are in good correspondence with the main structures in the unoccupied density-of-states of DF-LDA calculations. The electron energy-loss spectra present two structures which are also interpreted in terms of transitions between the bands obtained in the DF-LDA calculations.     

亚稳态FeCu固溶体微粉原子相互作用势的计算

本文介绍了亚稳态Fe50Cu50固溶体晶格常数的测量结果,应用金属结构的经典概念并考虑到原子核周围电子密度的高斯型球对称分布,导出了计算金属中一个原子的平均内能和两种不同金属原子相互作用势的普遍公式.对亚稳态Fe50Cu50合金原子相互作用势作计算,得到平衡时fcc-FeCu的晶格常数为0.36433 nm与实验测量结果接近,也与H.R.Gong等人对亚稳态FeCu合金的研究结论一致,证实了亚稳态Fe50Cu50合金是以fcc结构形式存在的固溶体.     

[M(H_2O)_3(NCS)_3](18-冠-6)[M=Cr(Ⅲ)或Fe(Ⅲ)]配合物的合成和物性表征

我们曾对二价的过渡金属与18—冠—6配合物的合成与表征进行研究。本文用凝胶法得到标题的两种三价过渡金属离子的组成类似韵配合物晶体,并对它们进行了组成分析和多项物理性质的测试和表征。而其中的铬配合物作者已进行X射线单晶结构分析。     

Mie散射研究聚合物合金相结构的形成及相尺寸分布

本文应用Mie散射理论研究了聚丙烯 /尼龙 1 0 1 0合金的相结构与形态 ,计算了相尺寸分布。其结果与电子显微镜及Rayleigh散射结果进行了比较。     

Compressive Stress Dependence of Magnetic Properties of Co66Fe4Ni1B14Si15 Alloy

The influence of compressive stresses on magnetic properties of Co₆₆Fe₄Ni₁B₁₄Si₁₅ amorphous alloy rings was investigated. In spite of low magnetostriction the stress sensitivity is significant. New method of applying stresses to a ring core is presented.