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<p>The performance of refractory metals such as W and Ta, key materials for extreme environments, depends critically on the relative density and grain size. Conventional sintering, however, suffers from a fundamental trade-off where densification inevitably triggers grain coarsening and property degradation. This work presents a novel cyclic upsetting–pressing (CUP) method that decouples densification from grain-boundary migration at significantly reduced temperatures. Using industrial-grade powders, bulk W with a relative density of 97.51%, an average grain size (<i>G</i><sub>ave</sub>) of 4.82&#xa0;μm, and a yield strength of 920.20&#xa0;MPa, as well as tantalum with a relative density of 99.16%, a grain size of 13.68&#xa0;μm, and a yield strength of 324.86&#xa0;MPa, were successfully consolidated at 1250 °C. Densification was achieved through stress-induced pore collapse during compression. Grain-boundary migration, which is responsible for grain size changes, occurred primarily via thermal activation during isothermal holding at 1250 °C. Under these conditions, W exhibited suppressed grain growth due to its high activation energy for grain-boundary diffusion, whereas Ta achieved grain refinement via recrystallization. The CUP process produced materials with significantly enhanced yield strength from multimechanism strengthening, and the W sample achieved a high fracture toughness of 15.67&#xa0;MPa m<sup>1/2</sup> owing to the synergistic effect of grain refinement and intragranular substructure formation. By successfully processing both brittle W and ductile Ta, the CUP technique establishes itself as a versatile strategy for fabricating refractory metals.</p> Graphical abstract <p></p>

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A novel cyclic upsetting–pressing method for the low-temperature densification of refractory metals

  • 期刊论文

  • 发表日期：

    2026年7月18日

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  • Xiao Hou,
  • Haozhi Ao,
  • Jianhui Zhong,
  • Dunqiang Tan,
  • Yingjun Wang

摘要

The performance of refractory metals such as W and Ta, key materials for extreme environments, depends critically on the relative density and grain size. Conventional sintering, however, suffers from a fundamental trade-off where densification inevitably triggers grain coarsening and property degradation. This work presents a novel cyclic upsetting–pressing (CUP) method that decouples densification from grain-boundary migration at significantly reduced temperatures. Using industrial-grade powders, bulk W with a relative density of 97.51%, an average grain size (Gave) of 4.82 μm, and a yield strength of 920.20 MPa, as well as tantalum with a relative density of 99.16%, a grain size of 13.68 μm, and a yield strength of 324.86 MPa, were successfully consolidated at 1250 °C. Densification was achieved through stress-induced pore collapse during compression. Grain-boundary migration, which is responsible for grain size changes, occurred primarily via thermal activation during isothermal holding at 1250 °C. Under these conditions, W exhibited suppressed grain growth due to its high activation energy for grain-boundary diffusion, whereas Ta achieved grain refinement via recrystallization. The CUP process produced materials with significantly enhanced yield strength from multimechanism strengthening, and the W sample achieved a high fracture toughness of 15.67 MPa m1/2 owing to the synergistic effect of grain refinement and intragranular substructure formation. By successfully processing both brittle W and ductile Ta, the CUP technique establishes itself as a versatile strategy for fabricating refractory metals.

Graphical abstract