- Email: [email protected]
Phase transformation in dilute U-TI alloys
378
Abstracts
ofthe Israel Society
state the weight ratio of the components was Cu:S = 70:30. An X-ray study of these layers showed that they were composed of a mixture of Cu-S and cu2-xs. In some places on the copper surface, groups of sulfur globules settled down. The diffusion of copper atoms into the sulfur was studied on these spheres. The sulfur spheres were found to transform into sulfide without changing their external form. The copper-sulfur reaction takes place at the boundary between sulfide and sulfur because of copper diffusion through the sulfide layers. The copper concentration in the sulfur spheres increases from 0 to 70% over several days. The copper surface exposed by removal of the sulfide layer is porous and has a low percent of sulfur (Z-3%), indicating that sulfur diffusion into copper is insignificant at room temperature. PHASE TRANSFORMATION IN DILUTE U-T1 ALLOYS G. Kimmel, A. Landau, J. Sariel and U. Admon Nuclear Research Center-Negev, Beer-Sheva, Israel
Ti is a stabilizer of the high temperature y-phase in dilute U-Ti .alloys. A variety of structures may be obtained when samples are cooled from the y-phase region to room temperature at different rates and conditions. We studied the decomposition modes of the v-phase of U-3.7 atomic % Ti alloy, at several isothermal heat treatments followed by quenching to room temperature. SEM and XRD techniques were employed. The thermal treatments were of three types. In the first the isothermal temperature was in the 660-710°C range, where the eutectoid reaction y + %+S takes place. In the second, for T = 500-640°C, the reaction is y -+ a+&. The third treatment was water quenching in which y transforms into a', a supersaturated solid solution having a distorted a-U structure. It was foundthat the content of the 6 phase was the highest after treatments of the first type, but undetectable after treatments of the third type. The grain morphology was strongly affected by the treatment employed. Treatments of the first type resulted in a lamellar pearlitic structure, showing a distinct phases separation. Treatments of the second type
for Electron Microscopy
gave a fine dispersion of 6 precipitates, coherent and acicular after short times and spheroidal after longer times. Treatments of the third type yielded a coarse, acicular and homogeneous structure. The three morphological types show resemblance to Pearlite, Bainite and Martensite in steels, respectively. The structures that were obtained axe shown, and an explanation of the reaction mechanisms based on their kinetics is suggested. USE OF THE SCANNING ELECTRON MICROSCOPE (SE?I)FOR MAPPING SITES OF ORGANIC MATTER IN PHOSPHATE ROCK E. Klein IMI
Institute Development,
for Research Haifa, Israel
and
A SEM fitted with an X-ray Energydispersive detector (EDS) can perform elemental microanalysis. This permits the discrimination of phases of different elemental composition. The main elements of organic matter, carbon,nitrogen, oxygen and hydrogen, are not detected by the conventional EDS techniques. However, if the orqanic matter contains sulfur, which is the case with many phosphate rocks, it can be mapped using the detectable sulfur signal as a tracer. The proviso is that the rocks do not contain sulfur-containing materials such as gypsum and pyrite. The results obtained by this technique agree well with those of fluorescent optical microscopy and electron back-scatter by SEM. ONE-DIMENSIONAL ATOMIC IMAGE PROFILES IN DARK FIELD EM A. P. Korn Biochemistry Institute of Israel
Department, Weizmann Science, Rehovot,
An unsettled question of theoretical interest regarding dark field electron microscopy is the determination of the true optimum defocus. Another matter is the degree of image asymmetry that may result from tilting the incident beam or shifting the aperture in order to block the unscattered beam. A third problem is the extent to which interfer-
Abstracts
ofthe Israel Society
state the weight ratio of the components was Cu:S = 70:30. An X-ray study of these layers showed that they were composed of a mixture of Cu-S and cu2-xs. In some places on the copper surface, groups of sulfur globules settled down. The diffusion of copper atoms into the sulfur was studied on these spheres. The sulfur spheres were found to transform into sulfide without changing their external form. The copper-sulfur reaction takes place at the boundary between sulfide and sulfur because of copper diffusion through the sulfide layers. The copper concentration in the sulfur spheres increases from 0 to 70% over several days. The copper surface exposed by removal of the sulfide layer is porous and has a low percent of sulfur (Z-3%), indicating that sulfur diffusion into copper is insignificant at room temperature. PHASE TRANSFORMATION IN DILUTE U-T1 ALLOYS G. Kimmel, A. Landau, J. Sariel and U. Admon Nuclear Research Center-Negev, Beer-Sheva, Israel
Ti is a stabilizer of the high temperature y-phase in dilute U-Ti .alloys. A variety of structures may be obtained when samples are cooled from the y-phase region to room temperature at different rates and conditions. We studied the decomposition modes of the v-phase of U-3.7 atomic % Ti alloy, at several isothermal heat treatments followed by quenching to room temperature. SEM and XRD techniques were employed. The thermal treatments were of three types. In the first the isothermal temperature was in the 660-710°C range, where the eutectoid reaction y + %+S takes place. In the second, for T = 500-640°C, the reaction is y -+ a+&. The third treatment was water quenching in which y transforms into a', a supersaturated solid solution having a distorted a-U structure. It was foundthat the content of the 6 phase was the highest after treatments of the first type, but undetectable after treatments of the third type. The grain morphology was strongly affected by the treatment employed. Treatments of the first type resulted in a lamellar pearlitic structure, showing a distinct phases separation. Treatments of the second type
for Electron Microscopy
gave a fine dispersion of 6 precipitates, coherent and acicular after short times and spheroidal after longer times. Treatments of the third type yielded a coarse, acicular and homogeneous structure. The three morphological types show resemblance to Pearlite, Bainite and Martensite in steels, respectively. The structures that were obtained axe shown, and an explanation of the reaction mechanisms based on their kinetics is suggested. USE OF THE SCANNING ELECTRON MICROSCOPE (SE?I)FOR MAPPING SITES OF ORGANIC MATTER IN PHOSPHATE ROCK E. Klein IMI
Institute Development,
for Research Haifa, Israel
and
A SEM fitted with an X-ray Energydispersive detector (EDS) can perform elemental microanalysis. This permits the discrimination of phases of different elemental composition. The main elements of organic matter, carbon,nitrogen, oxygen and hydrogen, are not detected by the conventional EDS techniques. However, if the orqanic matter contains sulfur, which is the case with many phosphate rocks, it can be mapped using the detectable sulfur signal as a tracer. The proviso is that the rocks do not contain sulfur-containing materials such as gypsum and pyrite. The results obtained by this technique agree well with those of fluorescent optical microscopy and electron back-scatter by SEM. ONE-DIMENSIONAL ATOMIC IMAGE PROFILES IN DARK FIELD EM A. P. Korn Biochemistry Institute of Israel
Department, Weizmann Science, Rehovot,
An unsettled question of theoretical interest regarding dark field electron microscopy is the determination of the true optimum defocus. Another matter is the degree of image asymmetry that may result from tilting the incident beam or shifting the aperture in order to block the unscattered beam. A third problem is the extent to which interfer-