Oxidation of Al-Co Alloys at High Temperatures

Authors :: Marián Palcut
Patrik Šulhánek
Ramūnas Skaudžius
Marián Drienovský
Libor Ďuriška
Žaneta Gerhátová
Ivona Černičková
Source :: Materials, Basel : MDPI, 2020, vol. 13, iss. 14, art. no. 3152, p. [1-17], Materials, Volume 13, Issue 14, Materials, Vol 13, Iss 3152, p 3152 (2020)
Publication Year :: 2020
Publisher :: MDPI AG, 2020.
Abstract: In this work, the high temperature oxidation behavior of Al71Co29 and Al76Co24 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-Al13Co4 and Z-Al3Co phases. The high temperature oxidation behavior of the alloys was studied by simultaneous thermal analysis in flowing synthetic air at 773&ndash 1173 K. A protective Al2O3 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 &times 10&minus 14 and 8.83 &times 12 g cm&minus 4 s&minus 1. The experimental activation energies of oxidation are 90 and 123 kJ mol&minus 1 for the Al71Co29 and Al76Co24 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.