Influence of coating thickness on microstructure, mechanical and LBE corrosion performance of amorphous AlCrFeTiNb high-entropy alloy coatings

The AlCrFeTiNb HEA coatings with different thickness were specially designed and successfully deposited on F/M steel tube using magnetron sputtering method. The dependence of microstructure, mechanical properties and LBE corrosion resistance on the coating thickness was systematically investigated. The increase in coating thickness makes the average inter-atomic distance of the amorphous AlCrFeTiNb coatings become larger, and the atomic arrangement become looser. With increasing coating thickness, the increase in nanohardness H, H/E and H3/E2 values were observed. The LBE corrosion test results indicated the increased parabolic oxide growth rate constant Kp (i.e. the increased corrosion oxidation rate) and the raised crack density with increasing coating thickness. The crack generation induced LBE penetration and internal oxidation of the coating, and the relevant crack-assisted internal oxidation mechanism is discussed intensively.