STRUCTURE SENSITIVE PROPERTIES OF INTERMEDIATE SOLID SOLUTIONS.
Final rept. 1 Sep 63-31 May 67,
NORTHWESTERN UNIV EVANSTON ILL DEPT OF MATERIALS SCIENCE
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The report is concerned with an investigation of the effects of point defects on various physical and optical properties of the intermetallic compounds NiAl, CoAl, NiGa, and CoGa. The optical properties of NiAl, CoAl, NiGa, and CoGa indicate that some of these alloys show free electron like behavior for photon energies below about 1 eV, but that others do not. The optical absorption bands that occur in NiAl at about 1 - 2 eV, 2.5 eV, 4.0 eV, and 5 eV have been associated with interband transitions and have been interpreted by the use of a simple rigid band model. CoAl, CoGa and NiGa alloys had an absorption band at 4.0 eV and CoAl and NiGa also had an absorption band at 1 - 2 eV. The 4.0 eV peak was common to all alloys and independent of composition, although the peak position varied slightly in photon energy from one alloy system to the next. The amplitude of the 2.5 eV band in NiAl was strongly compositionally dependent. The electrical resistivities of NiAl, CoAl, NiGa, and CoGa, measured as functions of temperature and composition indicate that these materials are metallic in nature, that the point defects are very important to the conductivity process, and that clustering of the point defects occurs when the composition departs from stoichiometry. Results from measurements of the Hall coefficient and the transverse magneto-resistance in NiAl indicate that a two band model may be necessary to explain the transport processes in NiAl. Author
- Metallurgy and Metallography