Search

This is the third technical report relating to work on Solid Electrolyte Battery Materials. During the past 18 months our efforts have had two major aims: one is to develop a novel technique for producing beta alumina solid electrolytes for use in the sodium-sulfur cell. The other is to search for new fast ion conducting materials for lithium and potassium ions, as well as to examine mixed conductor materials for potential application as electrodes in advanced secondary battery designs. The details and results of our efforts for the first year are presented in Technical Report No. 2. The present report covers the first six months of effort in the second year.

The program is composed of four separate programs as follows: Detection of X-Ray radiation; Superplasticity and warm working of metals and alloys; Synthesis of new types of catalyst materials; Development of elevated temperature electro-crystallization techniques., See also report dated 30 Jun 1974, AD784962.

The research program was initiated in order to study the problem of the mechanism or mechanisms by which dispersions of a stable second phase affect the deformation and annealing behavior of metals. In addition to studies directly associated with dispersions, a number of other investigations were conducted relating to various other aspects of the behavior of crystalline imperfections in metals. The significant results are indicated very briefly by reference to previous Technical Reports, papers published in the general technical literature, and Ph.D. dissertations that were either partially or wholly supported by this contract. Copies of the abstracts of the papers and the dissertations are appended. (Author)

Samples of iron containing 0.07 weight % nitrogen or 0.015 weight % carbon have been given treatments similar to those used in cold work peak (CWP) measurements and examined by transmission electron microscopy. It was observed that the unusual and non-reproducible behavior of the carbon CWP can be explained by a strong tendency for carbon to form grain boundary precipitates at temperatures below those used for CWP measurements. These precipitates dissolved at the temperatures used in the CWP measurements. There was no evidence for nitrogen precipitation at grain boundaries. There was no indication of precipitation along dislocations in either carburized or nitrided samples given treatments similar to those of CWP measurements. Although it is possible that sub-electronmicroscopic clustering had occurred, this observation supports the theories of the CWP that are based on continuous atmospheres rather than on individual precipitates. (Author)

Dislocation configurations at Luders fronts in tantalum which deformed by non-uniform discontinuous yielding have been examined. No contrast structure was observed in grain boundaries of recrystallized material unless evidence of sample mishandling or incomplete recrystallization was observed. No classical pileups were seen although slip bands were found in regions just ahead of a Luders band. Dislocation source action at or near grain boundaries was observed at Luders fronts and within Luders bands. The dislocation density was observed to increase during the passage of a Luders front and grain boundaries were seen to rapidly develop contrast structure during the passage of a Luders front. These observations are discussed in light of current knowledge concerning the mechanism of discontinuous yielding. (Author), See also AD-609 000.

A general treatment is presented of the temperature dependence of the kinetics of multi-step thermally activated reactions. The case of a stress-dependent reaction involving steps with different stress functions is discussed. Observations are included on the process of high temperature creep. (Author)

Several investigators have reported that internal oxidation of dilute alloys is accompanied by significant changes in electrical resistivity. In addition, the resistivity of materials containing dispersions has been shown to increase rapidly upon plastic deformation. This note reports a number of oxidation, deformation, and annealing experiments made on the Af - MgO alloy and to briefly discuss possible causes of the observed effects. (Author)

This program consists of two major parts: (1) Investigation of the feasibility of the use of a noval technique for the synthesis and fabrication of oxide solid electrolytes; and, (2) Search for new alkali metal ion-conducting solid electrolytes, and the determination of thier pertinent properties. The technique being investigated for the fabrication of oxides is based upon the controlled oxidation of infiltrated polymeric precursor materials. A fairly large number of ferrocyanide compounds have been prepared, their structures analyzed, and ionic mobility studies performed on them. Preliminary information has been obtained on several intermediate phases in the lithium-titanium oxide system. From a structural standpoint materials with the hollandite structure also appear promising as potential fast ion conductors. The potential of using graphite intercalation compounds as cathode materials is under investigation. The system graphite - CrO3 has been studied. A theroetical approach has been developed for the prediction of the lowest energy transport path through crystallographic structures containing tunnels.

Stacking faults were detected by x-ray measurements in cold rolled silver and dilute silver alloys. Small additions of magnesium, copper and oxygen were found to decrease the stacking fault probability of silver. Correlation of these observations with measurements of the twinning frequency and metallographic appearance suggests that the observed decrease in stacking fault probability is due to an increase in the relative stacking fault energy. (Author)

The structure of deformed internally oxidized alloys of silver containing magnesium and copper containing aluminum were studied by thin film transmission electron microscopy. With low to moderate amounts of strain, the deformation structure in the dispersion-hardened alloys was found to consist of a high density of dislocations arranged in a random distribution or in a very fine, but poorly defined, cell structure, depending on the fineness of the dispersion and amount of deformation. In contrast, both pure copper and silver show relatively large, distinct cell structures. The particular structures in the alloys are believed to result from particles acting as both dislocation sources and deflectors. The lack of a pronounced deformation texture and regions of severe local plastic curvature after heavy deformation can also be traced to the formation of dislocations on many slip systems and a lack of local concentrations of dislocations of predominantly one sign. (Author), See also AD-613 971.