The strengthening effects and mechanisms of alloying elements on interfaces for multiphase Ni-based superalloys: A first-principles study

The mechanical properties and thermal stability of multiphase Ni-based superalloys are highly determined by the interfaces between the strengthening precipitations and the matrix. In this work, the interface properties of the y/y'/y'' system are investigated using the first-principles calculations, and the strengthening mechanisms of alloying elements (3 d, 4 d and 5 d transition-metals) on the y/y'' and y'/y'' coexisting interfaces have been evaluated systematically. It was found that the matching configuration of the Ni (Center) + X (termination) is thermodynamically the most stable interface structure. The multi-interfaces doping results demonstrate that W, Re, Mo, Ta, Tc preferably occupy Nb-cp position and Fe, Co, Os tend to substitute Ni-fc position. Among these, W and Re have most significant effect on improving the bonding strength of y/y'' and y'/y'' interfaces synergistically. The dependence of interfacial cohesion on the metal radius and the con-centration of specific elements are discussed as well. The corresponding analysis of elec-tronic structures reveals that the strengthening effect of alloying elements can be ascribed to the increased chemical bonding strength between the doping atom and the nearest -neighbor host atom. The results of this work can shed light on developing novel Ni-based superalloys combinedly strengthened by y' and y'' phases.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).