Self-passivating (Re,Al)B(2) coatings synthesized by magnetron sputtering

(Re(0.67)Al(0.10))B(2) and (Re(0.74)Al(0.11))B(2) solid solution as well as Re(0.85)B(2) thin films were deposited by hybrid RF-DC magnetron sputtering. X-ray diffraction (XRD) showed that all films exhibit the ReB(2) (P6(3)/mmc) crystal structure. X-ray photoelectron spectroscopy (XPS) analyses performed on atmosphere exposed thin film surfaces suggest that ReB(2) corrodes, consistent with literature, by forming perrhenic acid (HReO(4)) already after two days, while (Re(0.74)Al(0.11))B(2) forms a self-passivating Al-oxide layer preventing corrosion in a time period ≥ 60 days. Hence, it is evident that Al additions to ReB(2) significantly increase the chemical stability during atmosphere exposure.