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<p>The United States lacks a stable domestic supply of <sup>99</sup>mTc, a critical medical imaging isotope generated from <sup>99</sup>Mo. Accelerator-based production using <sup>100</sup>Mo targets (aMo) introduces mechanical concerns due to the ductile-to-brittle transition temperature inherent to refractory metals like Mo. This study evaluates the tensile behavior of aMo targets from 25 to 1000&#xa0;°C, compared to powder-metallurgy-processed natural Mo (PMo) and cast-and-rolled Mo (RMo), both as-received and after 5&#xa0;ppm O<sub>2</sub> exposure in flowing He. RMo showed superior ductility (7.3% at 25&#xa0;°C, 48% at 1000&#xa0;°C) and strength, attributed to its fine, elongated grains and high geometrically necessary dislocation density. PMo exhibited variable ductility (up to 33%), while aMo remained brittle, with a maximum elongation of 10.4% at 600&#xa0;°C. EBSD analysis revealed weak texture in PMo and aMo, but high defect density in aMo limited dislocation mobility. This work links processing, microstructure, and deformation mechanisms to guide fabrication of ductile refractory targets.</p> Graphical abstract <p></p>

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An engineering perspective on evaluating mechanisms governing ductility in pure molybdenum

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年8月19日

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  • Holden C. Hyer,
  • Sebastien Dryepondt,
  • Thomas R. Muth,
  • Jim Nash

摘要

The United States lacks a stable domestic supply of 99mTc, a critical medical imaging isotope generated from 99Mo. Accelerator-based production using 100Mo targets (aMo) introduces mechanical concerns due to the ductile-to-brittle transition temperature inherent to refractory metals like Mo. This study evaluates the tensile behavior of aMo targets from 25 to 1000 °C, compared to powder-metallurgy-processed natural Mo (PMo) and cast-and-rolled Mo (RMo), both as-received and after 5 ppm O2 exposure in flowing He. RMo showed superior ductility (7.3% at 25 °C, 48% at 1000 °C) and strength, attributed to its fine, elongated grains and high geometrically necessary dislocation density. PMo exhibited variable ductility (up to 33%), while aMo remained brittle, with a maximum elongation of 10.4% at 600 °C. EBSD analysis revealed weak texture in PMo and aMo, but high defect density in aMo limited dislocation mobility. This work links processing, microstructure, and deformation mechanisms to guide fabrication of ductile refractory targets.

Graphical abstract