Magnetron-Sputtered Ni-Cr and Ti-Si Layers to Protect Ti-46Al-8Nb (at.%) Substrates Against Gas Absorption

Abstract

Ni-Cr and Ti-Si layers were deposited by magnetron sputtering on Ti-46Al-8Nb (at.%) substrates to suppress penetration of gases, which brings about undesirable changes in mechanical properties. Alloy samples with and without surface protection were subjected to interrupted oxidation at elevated temperature (700 and 800 °C) for up to 300 h. Selected mechanical properties as well as adhesion of surface layers were examined in the as-received and oxidized state. Analytical techniques used to characterize surfaces and cross sections of the samples included scanning electron microscopy and light microscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy and x-ray diffraction. Both investigated layers were sufficiently adherent and effective in hindering gas absorption at 700 °C; however, only Ni-Cr showed promising properties for higher-temperature applications.