Coherency strains in compositionally modulated systems and superlattices: spinodal decomposition and magnetoelasticity

Systems with a coherently modulated composition are considered with regard to their elastic properties. The (stress-free) coherency strains are considered in a new frame where the standard state is redefined on the basis of the property under study. These strains are used in the study of the thermodynamics of spinodal decomposition in solids with a (generally) anisotropic distortion into a cubic matrix. Finally, the influence of these strains is considered in the study of magnetostrictive effects in such modulated systems or strained-layer superlattices.     

Phase diagram of the Co-VC-NbC system

Conclusions The eutectic in the Co-VC system corresponds to the composition with 14% VC and a temperature of 1340 ± 20°C and the maximum solubility of vanadium carbide in cobalt is 6%. The Co-VC section is not a quasibinary section of the Co-V-C phase diagram.The eutectic in the Co-NbC system melts at 1360°C and contains 11–12% NbC.The as-cast alloys of the Co-VC-NbC system are in the metastable two-phase condition and the only carbide phase is a carbide of complex composition which is a three-component solid solution of vanadium and niobium monocarbides.The fusibility diagram of the equilibrium phase diagram of the Co-VC-NbC system is characterized by the four-phase eutectic equilibrium L Co + VC + NbC with the point of the ternary eutectic at 1330 ± 20°C and a composition of 11% VC, 4% NbC, and 85% Co. The Co-VC-NbC equilibrium phase diagram does not contain ternary compounds and the equilibrium phases are cobalt- and vanadium- and niobium carbide-base solid solutions. The total volume share of the carbide constituents of the ternary eutectic somewhat exceeds the share of carbide phases in the boundary eutectics Co-VC and Co-NbC.The total solubility of the carbides in cobalt does not exceed 2–3%.Translated from Poroshkovaya Metallurgiya. No. 3(315), pp. 80–87, March, 1989.     

A theoretical and experimental study of low-loss SAW filters with interdigitated interdigital transducers

A study of low-loss surface-acoustic-wave (SAW) interdigitated interdigital transducer (IIDT) structures is presented. A model based on mixed scattering matrices was used in the analysis. It is shown that the inherent comb frequency response of the IIDT can be smoothed by slanting the transducers in the structure. Alternatively, the combs can be enhanced to produce a compact low-loss feedback element for potential application in multimode oscillators. Experimental verification of the analysis is provided by a 3:2 slanted-finger IIDT filter with a 10% relative bandwidth of 5.9-dB insertion loss, and a comb filter with 13.4-dB insertion loss and comb spacing of about 3 MHz. The measured responses agree quite well with the theory.     

Plastic flow of polypropylene (PP) and PP-based blend

The evolution with temperature of the deformation mechanisms responsible for yielding in polypropylene (PP) and a PP-based blend is correlated to the molecular mobilities associated to glass transitions processes occurring in these materials. It is shown that the elementary local deformation event remains the same throughout the whole temperature range and that the onset of mobility only affects the average internal stress field \(\bar \sigma \) _i in which this thermally activated event takes place.     

Martensitic transformation in alloys of the system TiNi-TiCu prepared by ultrarapid melt cooling

Conclusion In alloys of the TiNi-TiCu system prepared in the form of thin tapes by ultrarapid melt cooling the B2-phase, which is unstable towards martensitic transformation B2B19, contains up to 35% Cu, whereas in bulk alloys prepared in the form of an ingot cooled at normal rates it contains about 10% Cu close to the M_S. In alloys containing up to 35% Cu there are no untransformed brittle phases preventing development of martensitic transformation throughout the volume of the material. The structure of alloys is quite uniform, particularly those obtained by crystallizing from the amorphous condition, and the grain size of the high-temperature phase is a fraction of a micron. The fine structure of alloys close to a globular at a high cooling rate. Thus, range of practically important alloys of the B2 type with inelastic behavior effects, e.g., the shape memory effect, is considerably expanded.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 38–41, November, 1988.     

Pharmacokinetics of anthracycline antibiotics deposited by polymers

An increase of doxorubicin concentration in different organs and tissues and its decrease in the peripheral blood were observed when studying pharmacokinetics of this drug administered in the 10% solution of polyvinylpyrrolidone. A prolonged and stable release of carminomycin from glue composition MK-10-0 "carminacryl" confirms an expediency of alpha-cyanoacrylate use for deposition of anthracycline antibiotics with the aim of loco-regional chemotherapy.     

Laser glazing of an Fe-C-Sn alloy

Morphology and geometry of melted zones, cooling rates, microstructure and microhardness in the laser-glazed Fe-4%C-10%Sn alloy have been investigated. The computer simulation on the basis of the moving gaussian source model was used successfully to predict the maximum width and depth of the melted zone and the cooling rate. The microstructure from the surface to the bottom of the laser-melted zone is a non-crystalline phase, dendritic grains and a microcrystalline zone successively. Values of the averaged-spacing of the non-crystalline phase are 0.205⁶ and 0.121⁹nm, respectively; twinned martensites, having an axial ratioc/a of 1.128, existed in dendritic grains, and carbides of Fe₃ C at the interdendritic regions; the microcrystalline zone was composed of -Fe and a new bet (a=0.415 nm,c=0.955 nm) phase. The different microstructure in the melted zone can be explained by the results of the heat flow calculation. A fine eutectic structure (-Fe + Fe₃C) was observed in heat-affected zones. Microhardness of the eutectic structure can be predicted by the empirical relation of fracture stress to the interlamellar spacing of pearlite.