Robert L. Fleischer

Nuclear tracks in solids. Principles and Applications

An extensive discussion of particle tracks in solids, quantitative methods for particle identification from them, and applications of the techniques in a number of fields are presented. Applications in geochronology, cosmic ray physics, meteoritic and lunar science, nuclear physics, chemical analysis, micro-chemical mapping, and radiation dosimetry are included. Each chapter contains numerous photographs and a substantial bibliography.

Intermetallic compounds : principles and practice

Partial table of contents: STRUCTURAL APPLICATIONS Ni3Al as a Single Phase (C. Liu & D. Pope) Silicides (K. Kumar) IMCs as Precipitates and Dispersoids (A. Ardell) ELECTRO-MAGNETIC APPLICATIONS Superconductor Applications (J. Stekly & E. Gregory) Magneto-Optical Applications (W. McGahan) Thermoelectric and Electrical Applications (M. Vedernikov) CHEMICAL AND METALLURGICAL APPLICATIONS Coating Materials (J. Nicholls) Electrochemical Applications (A. Vijh) MISCELLANEOUS APPLICATIONS Jewelry Applications (W. Rapson) Dental Amalgams (R. Waterstrat & T. Okabe) Bearing and Tribological Applications (W. Glaeser).

Substitutional solution hardening

Abstract Using the result of Stehle and Seeger for the volume expansion around a dislocation, the interaction of a screw dislocation with a substitutional impurity atom of different size from the solvent atoms is calculated. This result is then added to the interaction due to the different shear modulus of the solute atom. Yield strength measurements and shear modulus measurements have been made and, together with data from the literature allow comparison of the calculated relative effects of eleven different solute elements. The results imply that elastic interaction with screw dislocations controls the extent of solution hardening. Both atomic size and modulus contribute significantly to the hardening, but modulus difference supplies the dominant effect.

Solution hardening by tetragonal dist ortions: Application to irradiation hardening in F.C.C. crystals

Abstract It is pointed out that solution hardening is generally of two types, which are called gradual and rapid. Rapid hardening is attributed to tetragonal distortions, and a general statement of a theory is made. Specific calculations are applied to the case of the irradiation hardening of copper by neutron bombardment: Agreement is obtained with both the observed flux variation of the hardening and its absolute magnitude. For γ-irradiation of LiF similar agreement is found.

Rapid Solution Hardening, Dislocation Mobility, and the Flow Stress of Crystals

A theory is derived for impurity‐controlled dislocation mobility and the resultant temperature variation of the flow stress of lithium fluoride. The theory is suitable to crystals in which the hardening is primarily due to tetragonal lattice distortions such as result from the introduction of magnesium into lithium fluoride, these being defects whose interactions with dislocations have been calculated previously. Dislocation motion is envisioned as a series of thermally activated dislocation jumps through the stress fields produced by individual solute atoms. The theory predicts the observed temperature variation of the flow stress within 25%, approximate values of the slopes of the velocity‐stress relations, and the activation energy for dislocation motion.

Isotopic Disequilibrium of Uranium: Alpha-Recoil Damage and Preferential Solution Effects

Preferential loss of uranium-234 relative to uranium-238 from rocks into solutions has long been attributed to recoiling alpha-emitting nuclei. Direct evidence has been obtained for two mechanisms, first, recoil ejection from grains, and now release by natural etching of alpha-recoil tracks. The observations have implications for radon emanation and for the storage of alpha-emitting radioactive waste.

Techniques for geological dating of minerals by chemical etching of fission fragment tracks

Abstract Recent experiments on mica and natural glasses have shown that the number of irradiation damage tracks created by spontaneous fission of uranium atoms in these materials is a useful measure of geological time. In order to be able to extend this technique to other minerals it is necessary to be able to observe and identify fission tracks. Suitable chemical etching treatments are described for revealing such tracks in a variety of minerals, and rules are given for distinguishing fission tracks from dislocation and other defects. Dating results are given for two hornblendes and an apatite as examples of the procedures. Track studies also give a sensitive measure of the present and past distribution of uranium atoms in minerals.

High-strength, high-temperature intermetallic compounds

Materials that are solid at high temperatures are in demand for high-temperature structural applications, and materials that have high values of strength-to-weight and stiffness-to-weight are desired for aircraft and space applications. Basic properties that are insensitive to processing history can be used to provide a preliminary ranking of single-phase substances. A compilation is presented of 293 intermetallic compounds (or metal-metalloid compounds) that melt at T ⩾ 1500° C. By displaying the data by crystal structure on plots ofTm against the specific gravity ϱ candidates for optimum specific strength and specific stiffness can be recognized for materials that are likely to have similar plastic properties.

Recoiling alpha-emitting nuclei. Mechanisms for uranium-series disequilibrium☆

Abstract High-sensitivity experiments with particles that are strongly enriched in alpha-emitting nuclei show that damaged regions are produced that can be eroded by subsequent exposure to water. Direct ejection of recoil nuclei from solid grains is also observed. These observations appear to supply a basis for understanding disequilibria between 238 U and 234 U in natural samples that have been exposed to water. The two mechanisms observed are expected to act under different natural conditions.

Subterrestrial fluid convection: A hypothesis for long-distance migration of radon within the earth

Scattered observations suggest that radon can migrate through the earth for distances of ≳100 m, a process of great potential aid in both earthquake prediction and uranium exploration. It is noted that existing theories predict that fluid convection in the earth, driven by the local geothermal gradient, can occur in areas of relatively high permeability. The velocity of fluid flow may be sufficient to transport radon over large distances before it decays. The convection hypothesis also provides a possible explanation of seasonal effects that have been observed in local and general radon emanation into the atmosphere.