Exploring failure mode and enhancement mechanism of doped rare-earth elements iron-based/alumina-ceramic interface

This work implements a first-principles calculations method to explore the effects of rare-earth element dopants on the properties of the α-Al2O3 (0001)/γ-Fe (111) interface. The results show that the work of adhesion (Wad) of the doped-x (x=Ce, Y, Sc, La, Er, Yb, Gb, and Nd) Fe/Al2O3 interface is obviously greater than that of the non-doped interface, especially the doped-Y interface with the maximum binding strength, is selected as the model of tensile test. In contrast to the non-doped Fe/Al2O3 interface, the critical strain and tensile stress of the doped-Y interface increased from 0.5% to 8% and 6.88 to 13.55 GPa, respectively, indicating the introduction of rare-earth Y changed the failure mode of the Fe/Al2O3 interface from brittle to toughness fracture, significantly improving the mechanical performance of the Fe/Al2O3 interface. Further, electronic structure revealed that electron at local location being exhausted early induced by stretching is the signal of the structural failure. Furthermore, it is also found that the doped-Y atom segregate towards the middle of the Fe/Al2O3 interface, resulting in the Y-(p, d) orbits hybridized with O-s orbit in the range from −23.58 to −19.83 eV and Y-(s, p and d) orbits hybridized with Fe-s orbit in the range from −7.52 to −3.51 eV. As a result, the segregation behavior of the doped-Y atom appears to act as an adhesive at the Fe/Al2O3 interface, and then the electron orbital hybridization effect produced among atoms is enhancement mechanism of interface.