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<p>In this study, the tensile creep behavior of a MoSiBTiC alloy, a promising candidate for ultrahigh-temperature applications, was investigated in the temperature range of 1400–1700&#xa0;°C and the applied stress range of 100–300&#xa0;MPa, with a focus on the early stages of deformation. A non-contact method was employed to directly measure gauge length changes in the tensile specimens. The alloy exhibited non-steady-state creep behavior, characterized by a minimum creep rate attained during the transient regime at a true strain of approximately 0.02–0.03, followed by a transition to tertiary creep. Based on the strain of 0.01 (~ 1%), the Larson–Miller parameter was derived, and the temperature required to reach 1% strain under 170&#xa0;MPa in 125&#xa0;h was estimated to be approximately 1222&#xa0;°C. The stress exponent <i>n</i> determined from the Norton plots was on average 3.6 ± 0.2, and the apparent activation energy <i>Q</i><sub>c</sub> obtained from the Arrhenius plots was 515 ± 42&#xa0;kJ mol<sup>−1</sup>. A possible change in the deformation mechanism was suggested between 1500 and 1600&#xa0;°C, necessitating further investigation. Microstructural observations revealed the formation of voids and microcracks in the T<sub>2</sub> phase as early as the initial creep stage, up to a strain of ~ 0.01. Notably, the frequency of microcrack formation within the T<sub>2</sub> phase temporarily leveled off near the strain corresponding to the minimum creep rate, but increased markedly in the tertiary regime. These results suggest that microcracking within the T<sub>2</sub> phase is one of the dominant creep damage mechanisms in the MoSiBTiC alloy.</p>

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New insights into tensile creep behavior and early-stage damage in a MoSiBTiC alloy at ultrahigh temperatures

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年7月24日

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  • Ryuta Yanagiya,
  • Shiho Yamamoto Kamata,
  • Shunichi Nakayama,
  • Takahiro Kaneko,
  • Kyosuke Yoshimi

摘要

In this study, the tensile creep behavior of a MoSiBTiC alloy, a promising candidate for ultrahigh-temperature applications, was investigated in the temperature range of 1400–1700 °C and the applied stress range of 100–300 MPa, with a focus on the early stages of deformation. A non-contact method was employed to directly measure gauge length changes in the tensile specimens. The alloy exhibited non-steady-state creep behavior, characterized by a minimum creep rate attained during the transient regime at a true strain of approximately 0.02–0.03, followed by a transition to tertiary creep. Based on the strain of 0.01 (~ 1%), the Larson–Miller parameter was derived, and the temperature required to reach 1% strain under 170 MPa in 125 h was estimated to be approximately 1222 °C. The stress exponent n determined from the Norton plots was on average 3.6 ± 0.2, and the apparent activation energy Qc obtained from the Arrhenius plots was 515 ± 42 kJ mol−1. A possible change in the deformation mechanism was suggested between 1500 and 1600 °C, necessitating further investigation. Microstructural observations revealed the formation of voids and microcracks in the T2 phase as early as the initial creep stage, up to a strain of ~ 0.01. Notably, the frequency of microcrack formation within the T2 phase temporarily leveled off near the strain corresponding to the minimum creep rate, but increased markedly in the tertiary regime. These results suggest that microcracking within the T2 phase is one of the dominant creep damage mechanisms in the MoSiBTiC alloy.