Interfacial Reactions Between Anorthite (CaAl₂Si₂O₈) and Al 7075 Alloy at 850°C and 1150°C

Abstract

The present work reports an investigation of the interactions of Al 7075 alloy and anorthite at 850°C (150 h) and 1150°C (24 h). Transmission electron microscopy, electron probe microanalysis, X-ray diffraction, and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to identify the mineralogical and microstructural changes at the metalceramic interface. At 850°C, the phase formation mechanisms were (

In-situ scanning transmission electron microscopy study of Al-amorphous SiO2 layer-SiC interface

“…Our results clearly show that SiO 2 amorphous phase has different reaction mechanism with Al than the crystalline SiC. As mentioned before, the current theories suggest that reaction between metals and ceramics can either follow the dissolution [22,23,28,47] or the interdiffusion path [33][34][35][36][37][38]. The reason behind the different reaction mechanism for SiO 2 amorphous phase and SiC can be explained using the structural similarities of reaction products and the reactants for the crystalline ceramics.…”

“…In contrast to first theory, the second theory is based on interdiffusion of elements across the interface of the metal and the ceramic. This theory was applied in the previous works on Al-Si 3 N 4 [33], Al-CaAl 2 Si 2 O 8 [34,35], Al-BaAl 2 Si 2 O 8 [36,37], and Al-MgAl 2 O 4 [38] systems, in which elemental interdiffusion (e.g. Al 3?…”

Ionic interdiffusion as interaction mechanism between Al and Si3N4

“…Furthermore, only limited number of studies report the kinetics of these interactions. For example, research in the systems Al‐BaAl 2 Si 2 O 8 and Al‐CaAl 2 Si 2 O 8 showed that Al 3+ ‐Si 4+ interdiffusion along with oxygen vacancy formation (for charge neutrality) is the controlling the interaction. Formation of BaO·2Al 2 O 3 and CaO·2Al 2 O 3 at the Al‐BaAl 2 Si 2 O 8 and Al‐CaAl 2 Si 2 O 8 interfaces, respectively, and the presence of a minor amount of Al 2 O 3 at the interface supports the conclusion that the interaction mechanism is interdiffusion.…”

Characterizing modulated structures with first-principles calculations: a unified superspace scheme of ordering in mullite

“…In total 46 814 supercells were geometrically optimized (static relaxation) with the GULP code (Gale, 1997) applying the force model given by Matsui (1996). These FF parameters proved to give acceptable results for many silicate systems, including sillimanite, andalusite and mullite (Matsui, 1996;Lacks et al, 2005;Chen et al, 2008;Adabifiroozjaei et al, 2018). The main parameter of interest of the FF calculations was the total energy of a certain Al/Si ordering pattern to evaluate its stability.…”

“…All computational methods applied to crystal structure models require invariably fully occupied sites because fractional atoms lack a physical basis. If there are partially occupied atomic sites in the average structure, large defect structures can be generated with random or systematic approaches (Proffen & Neder, 1997;Okhotnikov et al, 2016) for further investigation including the simulation of diffuse scattering (Proffen & Neder, 1997) or molecular dynamics (Matsui, 1996;Lacks et al, 2005;Adabifiroozjaei et al, 2018). For example, to study the structure of highly disordered meta-kaolin an 18fold supercell with 282 atoms was used for calculations applying density functional theory (DFT) to support the refinement of the pair distribution function (White et al, 2010).…”