A High Resolution Electron Microscope Study of the Omega Transformation in Zr-Nb Alloys.
CORNELL UNIV ITHACA N Y MATERIALS SCIENCE CENTER
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High resolution direct lattice imaging and dark field electron microscopy were used to examine the omega phase transformation in Zr-Nb alloys. In the low Nb content alloys dark field electron microscopy was used to show that the omega phase consists of large domains 100-200A in diameter made up of small particles 3-6A in diameter. As the Nb content is increased the omega domains decrease in size until only 3-5A images are observed in alloys containing 15 wt. pct. Nb or more. The isolated particles are present over the range of composition from 8 to 30 wt. pct. Nb. Time sequence dark field micrographs taken at room temperature show that the omega domains in the low Nb alloys are changing with time. It is suggested that these observations indicate that fluctuations in structure between the beta and omega phases are occurring at room temperature. Modified author abstract
- Properties of Metals and Alloys