Study and theoretical explanation on high-temperature strength of ODS-W alloy

For tungsten (W), doping with second-phase particles is a commonly employed method to enhance its properties. Experiments have observed that oxide dispersion-strengthened tungsten alloys (ODS-W) exhibit superior and more stable ultimate tensile strength (UTS) at elevated temperatures. To elucidate this phenomenon, in situ tensile deformation experiments were conducted on ODS-W using transmission electron microscopy at temperatures up to 1273 K. Under the influence of temperature and tensile stress, a phase transition from BCC to FCC occurred near the oxide interfaces in W. This BCC–FCC phase transformation was corroborated by combining molecular dynamics simulations (MD) with density functional theory (DFT), confirming that the transformed FCC W matrix possesses an exceptional adhesion work, significantly enhancing the bonding strength at the W-oxide interfaces. Based on these observations, this work provides a plausible explanation for the high UTS retention of ODS-W at high temperatures. These findings offer valuable insights into the development of oxide-strengthened alloys for high-temperature applications and present a novel perspective on the mechanisms of second-phase reinforcement.