The new Iridium-Hafnium-Aluminum alloy thin films with excellent mechanical properties and oxidation resistance

Improving oxidation resistance has long been a challenge for hot end components in high temperature environments. We have fabricated a series of IraHfbAlc (at. %) alloy thin films by multi-targeted direct current magnetron sputtering (DC-MS) and have thoroughly investigated the microscopic mechanism of the films. More importantly, we for the first time prepared IraHfbAlc alloy thin films with a preferred (111) orientation substitution solid solution, which exhibits excellent mechanical properties and oxidation resistance. The minimum surface roughness (Ra) value of the IraHfbAlc alloy films was 0.7 nm, while the maximum hardness (H) and elastic modulus (E) exceeded 20 GPa and 330 GPa, respectively. The oxidized volatility of the Ir in the films was only 0.11 μm/h at 1300 °C (lower than most previously reported values, such as 0.5 μm/h), which greatly improved the lifetime of the film. Confirmation that lattice distortion induces the refinement of crystal-like order (CLO) in thin films, and solves the mystery of enhanced oxidation resistance. The findings provide important insights into the design of Ir-containing alloy coatings and offer new ideas in the field of high-temperature protection.