Effect of plastic deformation on the mechanical properties and the fine-structure parameters of Pb-Ca-Sn alloys

The specific features of structure formation in Pb-Ca-Sn alloys intended for battery current leads are considered. The effect of plastic deformation on the mechanical properties and the fine-structure parameters in Pb-0.1% Ca-0.3% Sn and Pb-0.05% Ca-1.1% Sn alloys is studied. The influence of the initial structure on the mechanical properties and the fine-structure parameters of the alloys is shown, and the variation of the alloy properties under plastic deformation is demonstrated.     

Effect of equal-channel multiangular pressing and heat treatment on the properties of an Nb-Ti-based superconductor

Effect of preliminary deformation induced by equal-channel multiangular pressing (ECMAP) in combination with hydroextrusion, drawing, and heat treatment on the structure and physicomechanical properties of a superconductor wire based on Nb-60 at % Ti alloy is studied. The optimal regime of ECMAP deformation is established.     

烧结温度对Mo_2FeB_2合金组织性能的影响

采用真空液相烧结法制备三元硼化物硬质合金,研究了烧结温度对三元硼化物硬质合金致密度、显微组织以及物相组成的影响.研究结果表明,三元硼化物硬质合金的密度和显微组织与烧结温度密切相关.当烧结温度较低时,合金中的硬质相晶粒发育不完全,且在粘结相中分布不均匀;烧结温度过高时,合金中的硬质相颗粒粗大,两者都会显著影响材料的性能.试样在1160～1210℃之间烧结时,随着烧结温度的不断增加,材料由固相烧结逐渐转化为液相烧结,试样的密度随着烧结温度的上升而逐渐增加,并确定试验最佳烧结温度为1210℃,此时材料的密度为8.23g/cm3,维氏硬度与洛氏硬度分别为8722.6N/mm2和75.3HRA,抗弯强度则达到1246.38MPa.通过对材料的显微组织与物相结构分析,阐述了该材料组织结构变化的原因.     

Effect of oxygen and fabrication variables on the mechanical properties of Zircaloy tubing

Abstract

The effects of oxygen concentration and fabrication variables on the mechanical properties of Zircaloy-2 tubing were investigated.

The strength can be adjusted with a sma11loss of ductility by controlling oxygen concentration. Cold reduction in the range of this study has a large effect on recrystallization and ductility but little on texture. The Q value, the ratio of the wall thickness reduction to the diameter reduction during fabrication, has a significant effect on texture, hydride orientation and deformation behaviour.

Tubes produced with a high Q value possess a superior combination of strength and ductility than tubes produced with a low Q value.

In burst testing, axial contraction contributes greatly to the circumferential elongation due to the difficulty of thickness reduction in high- Q tubes. In low- Q tubes, both thickness reduction and axial contraction, which is smaller than that in high-Q tubes, contribute to the circumferential elongation.

In practice, the optimum fabrication conditions for each fuel design must be determined.

Résumé

Les effets de la teneur en oxygène et du mode de fabrication sur les propriétés mécaniques de tubes en Zircaloy-2 ont été étudiés.

En controlant la teneur en oxygène, la résistance de ce matériau peut être ajustée avec une faible diminution de la ductilité. Dans le domaine de cette étude, l'écrouissage a une forte influence sur la recristallisation et la ductilité mais trés peu sur la texture. La valeur de Q (rapport entre la réduction de l'épaisseur des parois du tube et la réduction du diamétre) joue un rôle significatif sur la texture, sur l'orientation des hydrures et sur le comportement à la déformation.

Les tubes fabriqués avec une forte valeur de Q ont une meilleure combinaison de résistance et de ductilité.

Lors d'essais d'ec1atement, la contraction axiale contribue beaucoup a l'allongement circonférentiel pour les valeurs élevées de Q, car l'épaisseur des parois peut difficilement être réduite. Pour les faibles valeurs de Q la réduction de l'épaisseur et la contraction axialc, inférieure dans un cas précédent, contribuent simultanément à l'allongement circonférentie1.

En pratique il est nécessaire, pour tous les cas, de déterminer les conditions optimales de fabrication.     

Effect of oxygen and zirconium on the growth and superconducting properties of Nb3sn

The intermetallic compound Nb₃Sn is a type II superconductor of interest because of its high superconducting critical current density in high magnetic fields. One technique for forming Nb₃Sn is to react a molten tin alloy with a solid niobium-zirconium-oxygen alloy. It was found that the properties of Nb₃Sn are directly related to its microstructure, which is in turn directly related to the O: Zr atom ratio in the starting niobium foil. For a niobium alloy foil with an O:Zr atom ratio of 2, the resulting Nb₃Sn layer is fine grained and grows linearly with reaction anneal time until the entire Nb-Zr-O alloy core is consumed. This leads to a linear increase in critical current with time and a relatively constant critical current density. For a niobium foil without oxygen, the resulting Nb₃Sn grains are large and columnar and grow with a diffusion-limited layer growth rate. The resulting critical current density is low and decreases with reaction time. For a niobium alloy foil with an O:Zr ratio of >0 but <2, fine-grained Nb₃Sn is formed initially and grows with a linear layer growth rate, followed by a second layer of large, columnar-grained Nb₃Sn growing with a diffusion-limited rate. As a function of reaction anneal time and similar to the grain growth, the critical current initially increases linearly and then decreases. Formerly with GE Corporate Research & Development Schenectady NY     

Effect of ternary additions on the structure and properties of coatings produced by a high aluminum galvanizing bath

A Zn-Al eutectoid galvanizing alloy has been developed to address issues related to the growing environmental concern regarding leaching of zinc into the soil. The basic composition of the bath was selected close to the eutectoid point in the binary Zn-Al system, together with ternary additions in the form of Bi, rare earths (REs) and Si. The effects of these additions on the growth rate, microstructure, and corrosion properties of the coatings were investigated. Both Bi and REs showed a minimal effect on controlling the coating thickness developed with the eutectoid bath composition, which was about an order thicker than the commercially prevalent value of ∼80 μm. Addition of Si to the bath reduced the thickness of the coating to a level of around 30 μm. The morphology of the coatings, investigated in detail using scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction, showed the presence of three layers: interface layer, intermediate layer, and overlay. The dense interfacial layer mainly consisted of the Fe₂Al₅ phase; the intermediate layer contained two phases, an Fe-al phase and a Zn-rich phase; and the overlay had a composition close to that of the liquid bath. The intermediate layer contained a varying amount of porosity in all cases except in the coatings formed by the silicon containing bath. The thin, dense, and smooth coating obtained with the latter bath showed excellent resistance to corrosion, evaluated by field exposure as well as by electrochemical tests. An attempt is made to unravel the role of different elements in the formation of coating microstructure.     

Effect of oxygen concentration on the structure and properties of sintered silver-cadmium oxide composite contacts

The structure, corrosion resistance, and resistance to welding of silver-cadmium oxide contacts fabricated by sintering powder compacts in an inert gas containing a low concentration of oxygen were studied. Sintering in the absence or deficiency of oxygen produced structural changes in the material, accompanied by a reduction in the volume fraction of cadmium oxide and formation of a solid solution of cadmium in the silver matrix. Lowering the oxygen concentration and raising the sintering temperature resulted in a redistribution of cadmium and oxide phase in the solid solution, and impairment of the contact properties of the material. It appears that the effects observed are due to the decomposition of cadmium oxide. New technology for the manufacture of contacts by the powder metallurgical method is proposed, based on control of the oxygen concentration of the sintering atmosphere.     

Re-determination of the crystal structure of Ca2Y8Si6O26 and study on the luminescent properties of Ca2Y8Si6O26:Tb3+

The crystal structure of silicate oxyapatite Ca₂Y₈Si₆O₂₆ was indexed as hexagonal, space group P6₃/m, α=0.93515 nm, c=0.67872 nm, α=β=90°, γ=120°, V=0.5138692 nm³. Three strong peaks located at 32.079°, 32.595°, and 50.104° with d=2.7903, 2.74649, 1.8194 was in accordance with (211), (112), and (213) planes. The optimum concentration of Tb³⁺ in Ca₂Y₈Si₆O₂₆ to yield highest photoluminescence intensity was 10 mol.% of Y³⁺. The corresponding excitation spectrum consisted of an intense broad band from 220 to 260 nm. The photoluminescence measurements showed that the green emission originated from ⁵D₄?⁷F₅ was predominant in the measured range with strong doublet lines at 543 and 549 nm.     

Effect of oxygen on the mechanical properties of copper and copper-matrix composites hardened by melt-synthesized chromium carbides

Thermal analysis is used to study the saturation of the copper melt by oxygen from an oxygen-containing gas phase and the possibility of deoxidation of this melt by nanosized diamond–graphite, which enters in the reaction mixture used to synthesize chromium carbide in the production of copper-matrix composites, are studied. The oxygen and chromium carbide contents are found to affect the mechanical properties of copper and copper-matrix composites. Diamond–graphite is shown to have a high refining ability, which can substantially increase the plasticity of copper and copper-matrix composites. A low chromium carbide content is found to play a modifying role in grain refinement, and a high chromium carbide content is shown to cause the formation of a precipitation-hardened structure and an increase in the physicomechanical properties of copper-matrix composites.     

Effect of rolling with shear on the properties of steel 08G2S rods and wire

The hereditary effect of the structure of a wire rod on the structure and physicomechanical properties of the steel 08G2S wire produced by rolling with shear is studied in comparison with the wire produced according to the standard technology in OAO Metal Steel Krivoi Rog.