Phase stability and mechanical property trends for MAB phases by high-throughput ab initio calculations
arxiv(2024)
摘要
MAB phases (MABs) are atomically-thin laminates of ceramic/metallic-like
layers, having made a breakthrough in the development of 2D materials. Though
theoretically offering a vast chemical and phase space, relatively few MABs
have yet been synthesised. To guide experiments, we perform a systematic
high-throughput ab initio screening of MABs that combine group 4–7
transition metals (M); Al, Si, Ga, Ge, or In (A); and boron (B) focusing on
their phase stability trends and mechanical properties. Considering the 1:1:1,
2:1:1, 2:1:2, 3:1:2, 3:1:3, and 3:1:4 M:A:B ratios and 10 phase prototypes,
possible stabilisation of a single-phase compound for each elemental
combination is assessed through formation energy spectra of the competing
mechanically and dynamically stable MABs. Based on the volumetric proximity of
energetically-close phases, we identify systems in which volume-changing
deformations may facilitate transformation toughening. Subsequently, chemistry-
and phase-structure-related trends in the elastic stiffness and ductility are
predicted using elastic-constants-based descriptors. The analysis of
directional Cauchy pressures and Young's moduli allows comparing mechanical
response parallel and normal to M–B/A layers. Among the suggested most
promising MABs are Nb_3AlB_4, Cr_2SiB_2, Mn_2SiB_2 or the already
synthesised MoAlB.
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