Elastic properties of Mn-rich α intermetallic phase in engineering aluminum alloys: An ab initio study

The α intermetallic phase can be found in almost all aluminum alloys used in engineering, primarily because of the presence of unwanted but unavoidable impurities from primary production or recycling. There are ample examples showing that α intermetallic particles act as damage nucleation sites during forming operations. To achieve an in-depth understanding of these particles as damage nucleation sites, it is important to know their thermomechanical behavior, as well as their interactions with the matrix during production and service. Despite their importance, however, the mechanical properties of the α intermetallic phase, such as the elastic modulus and the thermal expansion, have not been very well studied. Here, we apply ab initio methods to study the mechanical properties of the α intermetallic phase, with the focus on two polymorphs of the Mn-rich α phase: Al114Mn24 and Al108Mn24Si6. Besides the ground-state elastic properties, the temperature-dependent thermal expansion coefficient and bulk modulus...