Materials Literature
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Abstract The stress-strain curves of Cu and Cu + Zn alloys containing alumina particles have been measured as a function of temperature, strain rate, composition, volume fraction and radius of the particles. Around room temperature the stress-strain curves of the Cu alloys are strongly temperature dependent and there…
Abstract Electron microscope studies of deformed single crystals of Cu and Cu + Zn alloys of various compositions containing small alumina particles show that the dislocation structures generated and associated with the particles consist generally of prismatic loops, Orowan loops as well as prismatic loops in some bra…
Unlike other ferroelectric perovskites, PbTi${\mathrm{O}}_{3}$ displays temperature-dependent Raman spectra consisting of underdamped modes, including the "soft" transverse-optical (TO) modes. Moreover, the softest TO mode shows linewidth divergence at the ferroelectric-to-paraelectric transition. Also in contrast to…
On the basis of the classical assumption of interatomic central forces, a method is proposed for the computation of the structure and energy of a grain boundary: It is applied to the particular case of symmetrical tilt boundaries around [100] in Al and Cu. The resulting curve shows that the interfacial energy is almos…
The influence of deviations from stoichiometry and titanium additions on the flow stress of polycrystalline Ni3Al has been determined in the temperature range — 196 to 1000 °C. The flow stress is found to be sensitive to small composition changes within the phase field. In particular, aluminium-rich deviations from st…
Experimental measurements of the low field d.c. conduction in both polycrystalline and single crystal yttria-stabilized zirconia are presented. Comparison shows that conduction in the single crystal material is little different from the polycrystalline counterpart. Results were obtained on a range of polycrystalline s…
Solid solutions in the system YPO4–YVO4, with and without 2 mol% of Tb3, were studied to determine the reason for the total inactivity of Tb in YVO4. The comparison of the diffuse reflectivity of Tb-containing solutions with that of Tb-free ones shows a uv absorption at energies below the absorption edge of YVO4 in ma…
Magnetic susceptibility and low-temperature specific-heat measurements have been made on several specimens of polycrystalline high-purity titanium, and in the case of the former measurement, on four single crystals. The calorimetric results are in good agreement with previously published data. A critically assessed av…
The quantum yield of a semiconductor thin-film photocathode, operating in the transmission mode, has been derived from the continuity equation and light multiple reflections within the film and the substrate. The fit between experiment and theory is good for hv<1.7 eV. The differences between experiment and the…
The optical constants of amorphous Ge films formed under well-defined conditions have been determined in the 0.1-25.0-eV spectral range. In the 0.1-1.8-eV range they were determined by analysis of precise reflectance and transmittance data ($\mathrm{RT}$), and in the 0.1-25.0-eV range by a Kramers-Kronig analysis of n…
Crystals of lactate dehydrogenase (LDH) were frozen by equilibration in a sucrose-ammonium sulfate solution, and then dipping into liquid nitrogen. The rate of radiation damage for frozen crystals was tenfold less than for crystals at room temperature. The physical properties of frozen crystals are discussed. Analysis…
Aluminum spheres were fired vertically into dry quartz sand in the light-gas gun facility at the NASA Ames Research Center. A velocity of 6.37 km/sec and a chamber pressure of 150 μ were used for all shots. Using an estimated impact pressure of 500 kb, heating of the target was computed to be 26% of the initial projec…
Abstract The morphology of porous anodic oxide films formed on aluminium in phosphoric acid electrolytes at constant current density or voltage, and under changing electrical or electrolytic conditions, has been studied quantitatively by electron microscopy. Replicas from film sections and from both film interfaces ha…
Using de Vries's model, we predicted theoretically that phase matching of optical third-harmonic generation can be achieved in cholesteric liquid crystals. The prediction was verified by measurements of third-harmonic generation from a mixture of cholesteryl chloride and cholesteryl myristate.
Amorphous clay separated from pedons of a highly weathered soil previously classified as Oxisol and an Ultisol of the Southern States and, from the surface horizons of an Oxisol and two Andepts of the tropics were studied by chemical, DTA, infrared and X‐ray analysis. Considerable amounts of amorphous material, 20–37%…
A study was made of the migration behavior of filaments in a 3-layer structure of 19 filaments. The filaments were twisted in two distinct forms: (a) ribbon-twisted and (b) cylindrical-twisted. The form of twisting was found to have an appreciable effect on the migration behavior of filaments. The frequency of migrati…
Abstract Expansion of a small spherical hole in a highly elastic solid is treated theoretically. Both elastic and surface energy terms are considered; the corresponding surface forces are assumed to be additive. The surface energy of the elastomer is assumed to be similar to that of simple liquids. Pressures or triaxi…
The nature of attack on unstressed iron and the mode of cracking in stressed iron during immersion in boiling Ca(NO3)2, NaNO3, NH4NO3 solutions and various mixed Ca2+ and NH4+ solutions have been followed by microscopic examination of specimens removed from the solutions at various fractions of the mean failure time a…
The x-ray diffraction characteristics of potassium acid phthalate (KAP) crystals have been measured with a vacuum two-crystal x-ray spectrometer using a flowing-gas proportional counter as a detector. The values of resolving power, percent reflection, and coefficient of reflection as determined from the (1, −1) positi…
Summary and Conclusions Thermal expansion measurements of composite systems containing hard dispersions embedded in brittle and semibrittle matrices indicate the importance of (1) the magnitude of the stress developed in the matrix and (2) the crack propagation behavior of the matrix. The thermal expansion of these co…