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<p>In this study, the cyclic oxidation behaviour of the polycrystalline Ni-based superalloy AD730™ was investigated. Cyclic oxidation tests were carried out in laboratory air at temperatures of 800&#xa0;°C, 900&#xa0;°C, 1000&#xa0;°C and 1100&#xa0;°C up to 500 cycles (1&#xa0;h per cycle). The oxidation behaviour of AD730™ approximately followed the parabolic rate law, and the average activation energy is about 312&#xa0;kJ/mol. At lower temperatures, a two-stage oxidation kinetics were observed, and the transition time decreased as the oxidation temperature increased. SEM observations indicated the formation of continuous but relatively irregular oxide layers with a surface nodular-type structure that thickened with increasing temperature. SEM–EDS analysis revealed that the oxide layers mainly consisted of a&#xa0;Cr<sub>2</sub>O<sub>3</sub> scale covered by TiO<sub>2</sub>. Aluminum was internally oxidized to form Al<sub>2</sub>O<sub>3</sub> as elongated precipitates, which grew along grain boundaries via branch-like growth. Furthermore, TiO<sub>2</sub> and TiN precipitates were found within the internal oxidation zone. The internal oxidation depth increased with rising temperature.</p>

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Investigations on the Cyclic Oxidation Behaviour of the Ni-Based Superalloy AD730™ at Elevated Temperature

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年4月19日

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  • K. Jahns,
  • A. Obrosov,
  • S. Weiß,
  • U. Krupp

摘要

In this study, the cyclic oxidation behaviour of the polycrystalline Ni-based superalloy AD730™ was investigated. Cyclic oxidation tests were carried out in laboratory air at temperatures of 800 °C, 900 °C, 1000 °C and 1100 °C up to 500 cycles (1 h per cycle). The oxidation behaviour of AD730™ approximately followed the parabolic rate law, and the average activation energy is about 312 kJ/mol. At lower temperatures, a two-stage oxidation kinetics were observed, and the transition time decreased as the oxidation temperature increased. SEM observations indicated the formation of continuous but relatively irregular oxide layers with a surface nodular-type structure that thickened with increasing temperature. SEM–EDS analysis revealed that the oxide layers mainly consisted of a Cr2O3 scale covered by TiO2. Aluminum was internally oxidized to form Al2O3 as elongated precipitates, which grew along grain boundaries via branch-like growth. Furthermore, TiO2 and TiN precipitates were found within the internal oxidation zone. The internal oxidation depth increased with rising temperature.