The Properties of Rare Earth Metals and Alloys.
Semi-annual technical rept. 1 Mar-31 Jul 72,
CALIFORNIA UNIV LOS ANGELES SCHOOL OF ENGINEERING AND APPLIED SCIENCE
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The high-temperature oxidation behavior of Ni3Al Ni-13 wo Al with and without additions of 0,5 yttrium has been studied over the range of 900 to 1200C in air. None of the commonly accepted rate laws were followed by the kinetics. Although the weight gains of samples containing yttrium were consistently 10 to 20 greater than those without yttrium, the steady-state scaling rates were identical. A quantitative X-ray diffraction technique was used to determine the kinetics of growth of the protective alpha-Al2O3 layer one of several oxides formed. The alumina growth followed the parabolic rate law under all conditions studied. The presence of yttrium greatly increased the short-time scale adherence. At longer times, however, the outer layer of NiAl2O4 and unreacted NiO spalled off along with some of the inner AlO3 layer. Author
- Properties of Metals and Alloys