Microstructure and He desorption behaviors of He charged FeCrNi-based films fabricated by direct current magnetron sputtering

• He-charged columnar nanocrystalline FeCrNi films were prepared by DC magnetron sputtering.
• Substrate temperature of 300 °C and He/Ar ratio 1:1 were the best sputtering parameters.
• Compact and uniform microstructure obtained at 300 °C resulted in stable, high hardness.
• Two He atoms' absorption/desorption mechanisms were revealed by TDS.

He-charged FeCrNi-based films were prepared at different temperatures in a mixed atmosphere of He and Ar by direct-current magnetron sputtering method. X-ray diffraction and energy dispersive spectrometry analysis confirmed the typical austenitic structure of the deposited FeCrNi films and the compositions were in good accordance with 304 stainless steel target. Cross-sectional scanning electron microscopy images revealed the dense columnar nanocrystalline structure of the fabricated FeCrNi films. Nanoindentation measurements showed that the film fabricated at 300 °C exhibited the highest hardness value of 11.5 GPa. He desorption from FeCrNi-based films was traced by thermal desorption spectroscopy; the relatively low He desorption temperature range (150 °C–450 °C) implied that the charged He atoms were mainly located in interstitial sites of FeCrNi-based films.