Surface energies, segregation, and fracture behavior of magnesium aluminate spinel low-index grain boundary planes

Review of grain boundary complexion engineering: Know your boundaries

“…The relationship between dopant and grain boundary plane is well demonstrated in rare earth doped magnesium aluminate (MgAl 2 O 4 ) spinel, as shown below. In pure spinel, atomistic simulations and fracture behavior of single crystals indicate that the {111} surface has higher energy than the {100} and {110} planes . Hasan et al showed that, while doping with rare earth ions lowers the surface energy of many low order planes, the {111} surface exhibits the greatest loss in energy.…”

“…Complexion diagrams that include both complexion type and their mechanical response have been developed in metal systems, including Ni‐Bi and Cu‐Zr . Recently, fracture toughness measurements were correlated with complexion types in Al 2 O 3 and MgAl 2 O 4 . Historically, complexion studies in ceramics have focused on grain boundary mobility.…”

“…In classic powder processing, the grain boundary character distribution is affected by sintering temperature and dopants . Therefore, to affect the initial distribution, one can consider treating the raw powders with dopants or heat treatments to influence their surface energy.…”

“…In many instances, grain boundary complexion transitions can be used to enhance the processing, properties, and performance of engineering materials. In Table , we provide a summary of recent applications and examples of complexion transitions, some of which can be considered as examples of grain boundary complexion engineering (GBCE). The idea of engineering grain boundaries to enhance the bulk properties of engineering materials is not new.…”

Structural and thermal properties of Zn-containing magnesium aluminate spinels obtained by wet chemical method

“…Spinels with the chemical formula of AB 2 O 4 , where A and B are cations in the tetrahedral and octahedral sites, respectively are a class of minerals [1,2]. Magnesium aluminate (MgAl 2 O 4 ) spinel (MAS), which is a member of this class, is a very attractive material used for a long time in various industrial applications due to its excellent structural properties including, high melting point, low dielectric constant, high refractoriness, excellent resistance to chemical attack, high electrical resistivity, low thermal conductivity and high resistance to radiation damage [3][4][5][6][7][8][9][10][11][12].…”