Scholarlink

<p>The pursuit of simultaneous high strength and ductility in metallic materials remains a critical challenge for engineering applications, particularly at cryogenic temperatures where conventional alloys often exhibit embrittlement. In this study, we demonstrate that an L-605 cobalt-based alloy (Co–20Cr–15&#xa0;W–10Ni, wt%) with a carefully engineered bimodal grain structure—comprising fine grains (FGs) and coarse grains (CGs)—exhibits exceptional strength-ductility synergy at cryogenic conditions. The alloy achieves an ultimate tensile strength exceeding 1.7 GPa, a yield strength above 1.1 GPa, and a uniform elongation over 45%. These outstanding mechanical properties originate from two synergistic mechanisms: (1) Cryogenic temperature effects: Enhanced solid-solution strengthening, grain boundary hardening, and dislocation interactions, coupled with γ→ε martensitic transformation triggered by reduced stacking fault energy. (2) Heterostructure effects: Accelerated martensite formation due to plastic strain incompatibility between fine grains (FGs) and coarse grains (CGs). Both mechanisms contribute to substantial work hardening, enabling simultaneous high strength and ductility. Our findings highlight bimodal grain structure engineering as a promising strategy for designing high-performance cryogenic structural materials.</p> Graphical Abstract <p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Ultrahigh Strength and Exceptional Ductility in a Bimodal-Grain-Structured Co–Cr–W–Ni Alloy at Cryogenic Temperature

  • 期刊论文

  • 发表日期：

    2026年3月17日

查看全文
  • Yanming Chen,
  • Changshun Wang,
  • Chenglin Li

摘要

The pursuit of simultaneous high strength and ductility in metallic materials remains a critical challenge for engineering applications, particularly at cryogenic temperatures where conventional alloys often exhibit embrittlement. In this study, we demonstrate that an L-605 cobalt-based alloy (Co–20Cr–15 W–10Ni, wt%) with a carefully engineered bimodal grain structure—comprising fine grains (FGs) and coarse grains (CGs)—exhibits exceptional strength-ductility synergy at cryogenic conditions. The alloy achieves an ultimate tensile strength exceeding 1.7 GPa, a yield strength above 1.1 GPa, and a uniform elongation over 45%. These outstanding mechanical properties originate from two synergistic mechanisms: (1) Cryogenic temperature effects: Enhanced solid-solution strengthening, grain boundary hardening, and dislocation interactions, coupled with γ→ε martensitic transformation triggered by reduced stacking fault energy. (2) Heterostructure effects: Accelerated martensite formation due to plastic strain incompatibility between fine grains (FGs) and coarse grains (CGs). Both mechanisms contribute to substantial work hardening, enabling simultaneous high strength and ductility. Our findings highlight bimodal grain structure engineering as a promising strategy for designing high-performance cryogenic structural materials.

Graphical Abstract