Molybdenum (Mo) has many advantages, like high melting point, corrosion resistance, and thermal conductivity. However, dispersion-strengthened Mo alloys often suffer from particle coarsening and segregation during long-term high-temperature services, which weakens their mechanical properties.

In a study published in Acta Materialia, researchers from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences developed a Mo alloy that combines high strength, good ductility, and excellent thermal stability at high temperatures.

Researchers introduced hafnium diboride (HfB₂) into Mo powder, and controlled its reaction with residual oxygen during sintering. This process generated high-density nanoscale Hf particles inside Mo grains.

Unlike conventional Mo alloys where strengthening particles tend to accumulate along grain boundaries, the Hf particles in Mo–Hf alloy were mainly distributed within the grains, which hinder dislocation movement and improve the alloy's deformation resistance.

The Mo–Hf alloy achieved a tensile strength of 754 MPa with good ductility at 400 °C. After long-term annealing at 1000 °C, the alloy retained stable mechanical properties, showing strong resistance to high-temperature degradation.

"During high-temperature processing, HfB₂ reacts with oxygen impurities in Mo powder to form uniformly distributed nanoscale hafnium particles. This distribution helps strengthen the alloy and maintain its mechanical performance under harsh conditions," said Assoc. Prof. ZHANG Yange, one of the authors of this study.

This study provides a practical approach for designing Mo-based materials with a balance of strength, ductility, and thermal stability, supporting their future applications in extreme high-temperature environments.