STAGE II WORK HARDENING IN CRYSTALS
Current theories of work hardening in stage II of stress–strain curves of f.c.c. crystals are reviewed critically. A detailed account is given of a theory described previously in outline by Hirsch (1964).
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Studies on melt spinning. II. Steady‐state and transient solutions of fundamental equations compared with experimental results
Abstract In the part installment of the present paper, the authors formulated the dynamics of melt spinning by introducing a set of fundamental equations that consist of the equations of heat, force, and material balances. Some steady‐state solutions were also given. Additional steady‐state solutions corresponding to…
The Enzymatic Acetylation of Chloramphenicol by Extracts of R Factor-resistant Escherichia coli
Chloramphenicol-resistant strains of Escherichia coli which carry the episomal resistance transfer factor R inactivate the antibiotic by enzymatic acetylation. In the presence of chloramphenicol and acetyl coenzyme A, cell extracts catalyze the formation of both a monoacetyl and a diacetyl derivative of chloramphenico…
GRAIN-SIZE DEPENDENCE OF FRACTURE IN COPPER–ALUMINIUM ALLOYS EMBRITTLED BY MERCURY
Polycrystalline specimens of α-phase copper–aluminium alloys of varying composition, amalgamated with mercury, have been deformed in tension in a soft tensile machine. In all cases, brittle intergranular failure occurred at stresses and strains below those required for fracture in air, the degree of embrittlement incr…
Energy Transfer in Tb^+3- and Eu^+3-Activated Y_2O_3
When excited by the proper wavelength, Tb+3 in Y2O3 transfers some of that energy to Eu+3 centers which subsequently emit 6125-Å light. The actual mechanism involves an initial high-energy excitation state (a broad band, indicating a perturbed activator state) which relaxes to one of the 5DJ states, from which emissio…
The Corona Threshold for Coaxial Cylinders in Air at High Pressures
The approximate corona-starting relation for concentric cylinders Ec/δ = A + B/√rδ, long established at lower gas densities, has been checked in air to δ = 35 over the respective ranges of inner and outer cylinder diameters of 0.0178 to 0.635 cm and 4.72 to 15.40 cm (Ec = corona-starting field at surface of inner elec…
Chemistry of Metal Hydrides. II. Spectroscopic Studies of Fluorovinylplatinum(II) Derivatives
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of Metal Hydrides. II. Spectroscopic Studies of Fluorovinylplatinum(II) DerivativesH. C. Clark and W. S. TsangCite this: J. Am. Chem. Soc. 1967, 89, 3, 533–539Publication Date (Print):February 1, 1967Publication History Published online1 May 2002Published inissue 1…
High‐Temperature Thermal Expansion of Certain Group IV and Group V Diborides
The thermal expansions of TiB 2 , ZrB 2 , HfB 2 , NbB 2 , and TaB 2 were measured to temperatures above 1600°C by an X‐ray method. Lattice constants were measured for each compound; each had the AlB 2 ‐type hexagonal structure. The mean linear thermal expansion coefficients were calculated from the data and are compar…
Phase Transitions in the System BaTiO 3 —KnbO 3
Solid solution formation in the system BaTiO 3 —KnbO 3 was established by X‐ray diffraction and dielectric measurements. Solid solutions with cubic symmetry were observed in the composition range from 4 to 90 mole % KnbO 3 at room temperature. The lattice parameter for the BaTiO 3 solid solutions increased with increa…
Calculation of Spark Breakdown or Corona Starting Voltages in Nonuniform Fields.
The processes leading to a spark breakdown or corona discharge are discussed very briefly. A quantitative breakdown criterion for use in high-voltage design is derived by which spark breakdown or corona starting voltages in nonuniform fields can be calculated. The criterion is applied to the sphere gap, and it is show…
THERMALLY ACTIVATED DEFORMATION OF α TITANIUM BELOW 0.4 T M
The effects of temperature, strain rate, and purity on the yield and flow stresses of α titanium at low temperatures (T < 0.4 T M ) are examined to ascertain the rate controlling dislocation mechanism. The effect of impurity content on the thermal component of the yield and flow stresses increases with the decrease in…
The Phase Transition in VO2
Magnetic properties in VO 2 have been studied in the temperature range from 100 to 380°K with the Mössbauer effect measurement of Fe 57 doped in VO 2 . Above and below the transition temperature, no internal field is observed. The observation indicates that VO 2 is paramagnetic even below the transition temperature an…
Temperature Dependence of the Elastic Constants of Molybdenum
The elastic properties of molybdenum single crystals have been measured using thin-rod resonance techniques as a function of temperature from −198° to over +650°C. Molybdenum behaves in a normal manner over this temperature range. Its elastic stiffness coefficients, with the exception of C12 which increased 3%, decrea…
Direct Observation of the Crystallization of Li 2 O‐Al 2 O 3 ‐SiO 2 Glasses Containing TiO 2
The nucleation and crystallization of Li 2 O‐Al 2 O 3 ‐SiO 2 glasses containing TiO 2 were investigated using transmission electron microscopy of thin sections produced from bulk samples. Phase separation occurs during cooling from the melt, and on heating, a large number of titanium‐aluminum crystals approximately 50…
PLASTIC ANISOTROPY OF TANTALUM, NIOBIUM, AND MOLYBDENUM
The stress–strain behavior of single crystals of tantalum, niobium, and molybdenum has been studied in both tension and compression in the temperature range 4.2–400 °K. The crystals were stressed in both the [Formula: see text] and the [Formula: see text] directions.At high temperatures, the yield stress of all three…
Antiplasticization. III. Characteristics and properties of antiplasticizable polymers
Abstract Antiplasticization is applicable to polymers which contain rigid, polar groups and stiff chains, such as many bisphenol polycarbonates and polyesters, 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol polycarbonates and polyesters, cellulose triacetate, and a commercial poly(sulfone ether). The stiffness, hardness, and…
Infrared Absorption Spectrometry in Clay Studies
Abstract The relationships between spectrum and structure in layer-silicates are reviewed, and applied in the study of structural changes occurring during the heating of montmorillonites up to dehydroxylation, and their subsequent rehydroxylation. Information given by infrared spectroscopy on the binding of water in e…
Mössbauer Studies of Ordered and Cold-Worked Fe–Al Alloys Containing 30 to 50 at. % Aluminum
Fe–Al alloys containing 30 to 50 at. % Al were investigated by Mössbauer spectroscopy. Both ordered alloys, having the CsCl or B2 structure, and alloys severely cold-worked by crushing were studied. At room temperature, all of the ordered alloys exhibit only paramagnetic lines, whereas the crushed alloys exhibit both…
Antiplasticization. II. Characteristics of antiplasticizers
Abstract By the incorporation of certain types of additives in bisphenol A polycarbonate, the modulus and tensile strength of the films are increased and the elongation is decreased. This effect is called antiplasticization, because the opposite results are obtained on plasticization—decreased modulus and tensile stre…
LATENT HARDENING AND THE FLOW STRESS IN COPPER SINGLE CRYSTALS
The latent hardening produced by straining copper crystals in single glide was investigated by measuring the flow stress on secondary systems. Specimens oriented for slip on these systems were spark cut from large prestrained crystals and tested in tension. These specimens did not always yield on the most highly stres…