Single-crystal elastic constants of Fe-15Ni-15Cr alloy

Resonant ultrasound spectroscopy (RUS) and pulse-echo (PE) superposition techniques have been used to determine the three independent elastic-stiffness constants C₁₁, C₁₂, and C₄₄ as a function of temperature for single crystals of 70Fe-15Ni-15Cr alloy. The values of the elastic moduli determined using RUS and PE are in very good agreement within the range of uncertainties. This particular ternary composition of Fe, Ni, and Cr undergoes an fcc-bcc structural phase transformation near 190 K resulting in a low-temperature ferromagnetic phase. The Debye characteristic temperature was determined to be 447 K from PE and 451 K from RUS measurements. The Zener elastic anisotropy A=2C₄₄/(C₁₁−C₁₂) is nearly constant: A=3.53±0.16 in Fe-Ni-Cr alloys with similar compositions. For these alloys, only small variations are observed in the Grüneisen parameter, γ≈2.08, and in the Poisson ratio, v _[hkl]=0.293±0.013.     

Processing and evaluation of 15Cr-15Mo nickel base superalloy

A Nickel base solid solution strengthened alloy has been made with a nominal chemical composition of 15Cr-15Mo (balance Ni) through vacuum melting route and was characterized in hot worked and heat-treated conditions. Processing parameters have been optimized to get the desired microstructure and mechanical properties. The alloy has shown very good mechanical properties at elevated temperatures as well as at cryogenic temperatures. Role of solution treatment temperature and correspondingly role of grain size on mechanical properties at different temperatures has also been evaluated and reported. Heat treatment cycle for application of alloy upto 700°C has been optimized. Properties of the alloy have been compared with similar class of alloys.     

N63-carboxamides of N15-alkyl and N15,N15-dialkyl derivatives of teicoplanin and deglucoteicoplanin

The synthesis and biological properties of a series of N63-carboxamides of 15-N-alkylated derivatives of teicoplanin A2 (CTA) and its aglycone (TD) are described. Among the compounds, those carrying hydrophilic groups or ionizable amino functions on the N15-alkyl chain are more soluble in water than parent N15-methylated or unmodified amides. Selected compounds were more active in vitro than CTA or TD, and a few of them were also slightly more efficacious in vivo than the parent antibiotics in streptococcal septicemia in the mouse. Their degree of activity varied with the structure and length of the N15-alkyl chains.     

High-performance liquid chromatographic separation of C-15-epimers of 15-methylprostaglandin E2 methyl ester and 15-methylprostaglandin E2

A high-performance liquid chromatographic system that permits quantitation of 15-methylprostaglandin E2 and its methyl ester is described. Separation from the corresponding C-15 epimers is effected by adsorption chromatography on microparticulate silica with refractive index detection.     

Allvac Ti-15Mo

Allac Ti-15Mo是一种亚稳态的B合金，化学成分（wt％）：N≤0．05，C≤0．10，H≤0．015（试样取自半成品轧材），Fe≤0．10，0≤0．20．Mo14．00—16．00，Ti余量。为了确保彻底熔炼和使Mo偏析降至最低，合金应在等离子电弧炉中熔炼，然后在VAR炉中重熔。合金的热处理制度为：在788—982℃（1400—1800°F）下退火1h，快速淬火至552℃（1025°F）以下。816℃（1500°F）下消除应力10min，快速淬火至552℃（1025°F）以下。合金具有良好的热、冷加工性能，机械性能也很好。合金通常在固溶退火和淬火条件下供货。     

15MnHP钢板的试制

本文叙述了柳钢用1200迭轧薄板机成材,轧后钢板采用喷水急冷、中温退火等工艺,成功地开发出15MnHP气瓶钢板。产品质量和性能均满足使用要求。     

15Cr-15Mn-0.4N不锈钢冶金缺陷分析

结合现场生产工艺,分析了15Cr-15Mn-0.4N不锈钢棒材圆心部位点状偏析形成的机理.结果表明,点状偏析是由于存在大量的含Nb析出物以及聚集的大量夹杂物而形成的.调整AOD吹氮工艺,加强钢液的吹氩搅拌操作,以及在加入合金后保持充分的冶炼时间,有利于减少此类偏析现象和夹杂物缺陷的发生.     

Ti3Al对TiCu15Ni15钎料组织的影响

分别以0％，25％，50％，75％，100％比例的Ti3A1替换TiCu15Ni15中Ti，对所得的钎料进行组织形貌及成分分析。研究结果表明：钎料合金由先结晶低Cu，Ni含量相和后结晶的高Cu，Ni含量相组成，随TiaAl增加。低Cu，Ni含量相减少，高Cu，Ni含量相增加，同时由于Nb含量增加，背散射图像发生变化，先结晶相由灰色逐渐变为亮白色，后结晶相成分偏析增加，先结晶高Nb相为灰色，后结晶低Nb相为黑色，至5^#合金形态发生显著变化，灰色相由块团状变为短条或片状，其中央为白色边缘为灰色，这将引起性能变化。     

TA15钛合金大棒与ZTA15精铸件的化学成分波动研究

主要介绍了我国航空ZTA15精铸件用TA15钛合金棒材的20余吨原料试制情况,重点是棒料和铸件的化学成分变化情况,同时分析了大棒的显微组织和力学性能。     

GCr15钢的韧化处理

根据不均匀奥氏体加热淬火原理，通过加热过程控制，使ＧＣｒ１５钢淬火后既细化了奥氏体晶粒又细化了马氏体，同时还获得了低碳板条马氏体及呈薄状或集聚态的残余奥氏体包围在碳化物周围的组织，该方法是韧化ＧＣｒ１５钢的有效途径。     

Streckgrenzenverhalten des Stahls C 15

Im Rahmen dieser Arbeit soll der athermische, korngrößenunabhängige Anteil der Streckgrenze experimentell bestimmt werden. Weiterhin wird der Versuch gemacht, eine Gesetzmäßigkeit ähnlich der Petch-Gleichung für die Lüders-Dehnung herauszuarbeiten. Zur Lösung der ersten Aufgabe wurde der Stahl C 15 im Zugversuch getestet. Hierbei wurden die Korngröße und die Versuchstemperatur variiert. Zur Ermittlung der Abhängigkeit der Lüders-Dehnung von anderen Werkstoffkenngrößen wurden neben eigenen Experimenten weitere aus dem Schrifttum bekannte Versuchsergebnisse herangezogen.     

Genomic structure and chromosomal localization of the human interleukin 15 gene (IL-15)

The morphologic and functional characteristics of cultured hair follicle dermal papilla (DP) cells, dermal sheath (DS) cells and interstitial dermal fibroblasts (DF cells) derived from human scalp tissue are compared. DP and DS cells, but not DF cells, showed aggregative behavior at a preconfluent density. All three types of cells stained positive for type I collagen, type IV collagen, laminin and heparan sulfate proteoglycan. Only DP and DS cells expressed smooth muscle alpha-actin. DP and DS cells also synthesized more glycosaminoglycans (GAG) than DF cells, while there was no significant difference between DP and DS cells in GAG synthesis. Ultrastructurally, 7 out of 10 strains of DP and 2 out of 10 strains of DS cells were found to form intranuclear rodlets, while none of the 10 strains of DF cells examined formed intranuclear rodlets. The conditioned medium of the three types of cells was collected and tested for the presence of interleukin (IL)-1 beta, tumor necrosis factor (TGF)-beta 2, IL-6, platelet-derived growth factor-AB, epidermal growth factor, b-FGF, GM-CSF, insulin-like growth factor (IGF)-1 and HGF (hepatocyte growth factor) by ELISA or RIA. Among the tested cytokines and growth factors, TGF-beta 2, IL-6 and IGF-I were detectable in at least some conditioned media. The others were undetectable. There was no significant difference in the production of IL-6 and IGF-I among the three types of cells. In contrast, DP cells produced the highest levels of TGF-beta 2, DS cells produced intermediate levels of TGF-beta 2, and DF cells produced the lowest levels of TGF-beta 2. DP and DS cells are morphologically and functionally different from the nonfollicular, interstitial DF cells. Moreover, the presence of some minor biologic differences between DP and DS cells suggests that they represent follicular mesenchymal cells in different functional or differentiation states.     

Development of microstructures in Fe−15Ni−15Cr single crystal electron beam welds

A detailed analysis of the microstructures produced in an autogenously welded single crystal of Fc−15Ni−15Cr was performed in order to investigate the relationship between growth crystallography and solidification behavior. Electron beam welds were made at various speeds on the (001) surface of single crystals in either the [100] or [110] directions. A geometrical analysis was carried out in order to relate the dendrite growth velocities in the three 〈100〉 directions to the weld velocities for the different crystallographic orientations examined. From this analysis, the preferred dendrite trunk directions were determined as a function of the solidification front orientation based upon a minimum velocity or minimum undercooling criterion. A thorough examination of the weld microstructures and a comparison with the geometrical relationships developed in this work permitted a three-dimensional reconstruction of the weld pool shape to be performed. In addition, the dendrite spacings were measured, and the variation in spacings as a function of growth velocity was compared with theoretical predictions. It was found that the range of velocities over which dendritic growth is expected agreed with the experimental findings, and, furthermore, the change in dendrite spacing with growth velocity varied as predicted by theory. These results clearly demonstrate the effect of crystallography on the micro-structural development during weld pool solidification. The results also show that the resultant microstructures and pool shapes can be explained by geometrical analysis in conjunction with existing solidification models. M. R{upappaz}, formerly Visiting Scientist with the Metals and Ceramics Division, Oak Ridge National Laboratory, is permanently affiliated with the Laboratoire de Métallurgie Physique, Ecole Polytechnique Fédérale de Lausanne     

Wild-type p53-mediated down-modulation of interleukin 15 and interleukin 15 receptors in human rhabdomyosarcoma cells

We recently reported that rhabdomyosarcoma cell lines express and secrete interleukin 15 (IL-15), a tightly regulated cytokine with IL-2-like activity. To test whether the p53-impaired function that is frequently found in this tumour type could play a role in the IL-15 production, wild-type p53 gene was transduced in the human rhabdomyosarcoma cell line RD (which harbours a mutated p53 gene), and its effect on proliferation and expression of IL-15 was studied. Arrest of proliferation was induced by wild-type p53; increased proportions of G1-arrested cells and of apoptotic cells were observed. A marked down-modulation of IL-15 expression, at both the mRNA and protein level, was found in p53-transduced cells. Because a direct effect of IL-15 on normal muscle cells has been reported, the presence of IL-15 membrane receptors was studied by cytofluorometric analysis. Rhabdomyosarcoma cells showed IL-15 membrane receptors, which are down-modulated by wild-type p53 transfected gene. In conclusion, wild-type p53 transduction in human rhabdomyosarcoma cells induces the down-modulation of both IL-15 production and IL-15 receptor expression.