| Summary: | In this work, the high temperature oxidation behavior of Al<sub>71</sub>Co<sub>29</sub> and Al<sub>76</sub>Co<sub>24</sub> alloys (concentration in at.%) is presented. The alloys were prepared by controlled arc-melting of Co and Al granules in high purity argon. The as-solidified alloys were found to consist of several different phases, including structurally complex m-Al<sub>13</sub>Co<sub>4</sub> and Z-Al<sub>3</sub>Co phases. The high temperature oxidation behavior of the alloys was studied by simultaneous thermal analysis in flowing synthetic air at 773–1173 K. A protective Al<sub>2</sub>O<sub>3</sub> scale was formed on the sample surface. A parabolic rate law was observed. The rate constants of the alloys have been found between 1.63 × 10<sup>−14</sup> and 8.83 × 10<sup>−12</sup> g cm<sup>−4</sup> s<sup>−1</sup>. The experimental activation energies of oxidation are 90 and 123 kJ mol<sup>−1</sup> for the Al<sub>71</sub>Co<sub>29</sub> and Al<sub>76</sub>Co<sub>24</sub> alloys, respectively. The oxidation mechanism of the Al-Co alloys is discussed and implications towards practical applications of these alloys at high temperatures are provided.
|
|---|