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<p>Ni-based single-crystal superalloys are widely used for turbine blades in aerospace engines. The turbine blades are continuously subjected to creep damage, which is difficult to be detected during service. In this work, the stress-dependent creep behavior of a DD32 single-crystal nickel-based superalloy at 850&#xa0;°C was investigated. Four stages of creep deformation were found in the curves of creep strain rate versus the time. Results indicate that the durations of the four creep stages are all increased with a decrease in applied stress from 750&#xa0;MPa (ruptured at 7.8&#xa0;h) to 660&#xa0;MPa (ruptured at 129.6&#xa0;h), while the maximum and minimum creep rates are decreased at corresponding creep stress. Under high creep stress (750&#xa0;MPa), the increase of void volume was resulted by two types of casting pores and micro-crack formation around MC carbides. Under low applied stress (660&#xa0;MPa), the formation of TCP phase was prone to creep damage in the form of creep voids, leading to the increasing volume and number of creep voids. Compared with the applied stress ranged from 660 to 725&#xa0;MPa, a reduction in hardness is associated with the dislocation-based creep mechanisms. The relation between stress-dependent creep behaviors and microstructural degradation such as TCP phase and creep voids was established.</p>

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An experimental study on stress-dependent creep behaviors and void evolution of Ni-based single-crystal alloy

  • 期刊论文

  • 发表日期：

    2026年4月22日

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  • Zhiqiang Wang,
  • Yixi Wang,
  • Yuxuan Song,
  • Zhihui Cai,
  • Yuanlong Lin,
  • Yuebing Li,
  • Weiya Jin,
  • Zengliang Gao

摘要

Ni-based single-crystal superalloys are widely used for turbine blades in aerospace engines. The turbine blades are continuously subjected to creep damage, which is difficult to be detected during service. In this work, the stress-dependent creep behavior of a DD32 single-crystal nickel-based superalloy at 850 °C was investigated. Four stages of creep deformation were found in the curves of creep strain rate versus the time. Results indicate that the durations of the four creep stages are all increased with a decrease in applied stress from 750 MPa (ruptured at 7.8 h) to 660 MPa (ruptured at 129.6 h), while the maximum and minimum creep rates are decreased at corresponding creep stress. Under high creep stress (750 MPa), the increase of void volume was resulted by two types of casting pores and micro-crack formation around MC carbides. Under low applied stress (660 MPa), the formation of TCP phase was prone to creep damage in the form of creep voids, leading to the increasing volume and number of creep voids. Compared with the applied stress ranged from 660 to 725 MPa, a reduction in hardness is associated with the dislocation-based creep mechanisms. The relation between stress-dependent creep behaviors and microstructural degradation such as TCP phase and creep voids was established.