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<p>The effects of grain coarsening via annealing on the high-temperature compression properties of a bimodal Mo-12Si-8.5B-0.57&#xa0;wt.% La<sub>2</sub>O<sub>3</sub> alloy have been investigated. The as-hot-pressed (HP) alloy initially possessed a micron/submicron bimodal α-Mo matrix with dispersed submicron Mo<sub>3</sub>Si and Mo<sub>5</sub>SiB<sub>2</sub>. Annealing led to grain coarsening: after 3&#xa0;h, micron Mo<sub>3</sub>Si and Mo<sub>5</sub>SiB<sub>2</sub> were distributed in a micron bimodal α-Mo matrix with coarse-grained (CG) and fine-grained (FG) regions, and after 6&#xa0;h, the bimodal α-Mo matrix transitioned to a micron unimodal α-Mo matrix. At 1000°C, the as-HP-ed alloy demonstrated the highest compressive strength (1542&#xa0;MPa) but suffered from premature brittle fracture. Grain coarsening improved compressive plasticity by enhancing dislocation storage. At 1200–1400°C, prolonged annealing increased the strength of alloy. Notably, at 1400°C, the compressive strength (327&#xa0;MPa) of alloy annealed for 6&#xa0;h was 170% higher than that of as-HP-ed alloy. The strengthening was driven by reduced grain boundary sliding, work hardening of coarsened bimodal or unimodal microstructure, and Orowan strengthening of La<sub>2</sub>O<sub>3</sub>. At 1400°C, the micron α-Mo of as-HP-ed alloy preferentially underwent dynamic recrystallization, delaying deformation in submicron regions and providing good softening resistance. However, the coarsened bimodal and unimodal microstructure accelerated recrystallization of micron CG/FG α-Mo and intermetallics regions, slightly reducing softening resistance.</p>

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Enhancing the High-Temperature Compression Property of Bimodal Mo-Si-B Alloy via Coarsening Grain

  • 期刊论文

  • 发表日期：

    2026年1月26日

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  • Rui Li,
  • Xubo Liang,
  • Xuan Chen,
  • Bin Li,
  • Juan Wang,
  • Jiachen Zhang,
  • Caixia Wang,
  • Guojun Zhang,
  • Pengcheng Guo

摘要

The effects of grain coarsening via annealing on the high-temperature compression properties of a bimodal Mo-12Si-8.5B-0.57 wt.% La2O3 alloy have been investigated. The as-hot-pressed (HP) alloy initially possessed a micron/submicron bimodal α-Mo matrix with dispersed submicron Mo3Si and Mo5SiB2. Annealing led to grain coarsening: after 3 h, micron Mo3Si and Mo5SiB2 were distributed in a micron bimodal α-Mo matrix with coarse-grained (CG) and fine-grained (FG) regions, and after 6 h, the bimodal α-Mo matrix transitioned to a micron unimodal α-Mo matrix. At 1000°C, the as-HP-ed alloy demonstrated the highest compressive strength (1542 MPa) but suffered from premature brittle fracture. Grain coarsening improved compressive plasticity by enhancing dislocation storage. At 1200–1400°C, prolonged annealing increased the strength of alloy. Notably, at 1400°C, the compressive strength (327 MPa) of alloy annealed for 6 h was 170% higher than that of as-HP-ed alloy. The strengthening was driven by reduced grain boundary sliding, work hardening of coarsened bimodal or unimodal microstructure, and Orowan strengthening of La2O3. At 1400°C, the micron α-Mo of as-HP-ed alloy preferentially underwent dynamic recrystallization, delaying deformation in submicron regions and providing good softening resistance. However, the coarsened bimodal and unimodal microstructure accelerated recrystallization of micron CG/FG α-Mo and intermetallics regions, slightly reducing softening resistance.