Selective oxidation of zirconium in Zr2Cu

The high-temperature oxidation of Zr2Cu in dry oxygen is characterized by s elective oxidation of zirconium. The excess of copper is accumulated in the matrix alloy at the alloy-oxide interface forming the Zr8Cu5 phase. The ox ide layer consists of monoclinic ZrO2 and a small amount of CuO. Additional ly, tetragonal ZrO2 appears up to 873 K at the surface, and Cu2O is formed above 873 K, deeper in the oxide layer. The reaction kinetics obeys a parab olic rate law. An activation energy of 54.4 kJ/mol has been estimated in th e temperature range 773-1123 K. An anomalous decrease of the oxidation rate occurs at 1155-1223 K, after a strong reaction at 1073-1150 K.