High temperature surface oxidation response of Ni50Ti49Ta1 and Ni50Ti47Ta3 shape memory alloys

Abstract

The phase transformation characteristics and isothermal oxidation behavior of ternary Ni50Ti49Ta1 (at.%) and Ni50Ti47Ta3 (at.%) alloys were investigated through differential scanning calorimetry and thermogravimetric analysis techniques in addition to surface morphology captured by scanning electron microscopy. It was found that the ambient temperature and chemical composition are important factors in the oxidation behavior of the alloys in oxygen atmosphere. The oxidation constants were linearly increased with oxidation temperatures ranging between 850 and 1150 degrees C. The activation energies were determined to be 283.54 kJ/mol and 249.38 kJ/mol for the Ni50Ti49Ta1 (at.%) and Ni50Ti47Ta3 (at.%) alloys, respectively.