Vacancy mediated alloying strengthening effects on Al/Al3Zr interface and stabilization of L1(2)-Al3Zr: A first-principles study

摘要

The presence of L1(2)-Al3Zr, can drastically improve the strength of Al alloys, however, the L1(2)-Al3Zr is a metastable structure and prone to have phase transformation at the Al/Al3Zr (alpha/(beta') interface. Therefore, it is very important to prevent the phase transformation and stabilize the metastable structure. In this work, the first-principles calculations method based on density functional theory was used to explore the intrinsic mechanism of adding solute atoms to effectively control the phase transition proposed in the experimental research. Based on the determination of the optimal doping sites of atoms, the calculation of the diffusion energy barrier proves that the introduction of alloying elements does hinder the diffusion of atoms, thus effectively suppressing the phase transition process at the interface. From the perspective of Griffith work of fracture (G), the effects of alloying element and vacancy on the interfacial bonding strength were considered. There is the best strength effect while the alloying atom replaces the beta'-Al site at the interface with V-Al or without V-Al, and among the four elements studied, the alloying effect of Nb is the best, and Cu is relatively poor. In addition, the calculation results of the Griffith work of fracture were explained by the electronic local function. The introduction of alloying element makes the change of the degree of electron localization of Al atoms nearby is an important reason for the interfacial bonding strength. The obtained results in the present work instructive for the interfacial strengthening mechanisms and it may serve as a design tool for Al-Zr alloys with desired properties. (C) 2020 Elsevier B.V. All rights reserved.