High-throughput combinatorial study of the effect ofMsite alloying on the solid solution behavior ofM2AlCMAX phases

Abstract

In this work, a systematic investigation of the alloying behavior on the M sub-lattice of M 2 AlC, where M is Ti,V,Zr and Hf with elements in the first transition metal row as well as Ca and Sc is carried out via a combination of alloy theoretic approaches and Density Functional Theory for 41 alloy systems. The cluster expansion formalism is used to explore the configurational space in ternary MAX phases. On the basis of their solid-solution behavior, the alloys are classified into three regimes: phase separation, weak ordering and strong ordering. Observed trends are investigated in terms of indicators at the electronic and structural levels. For the systems showing ordering, the ordered structures are identified and their structural and electronic properties are investigated. The likelihood of some of the systems to exist as solid solutions at finite temperature is discussed.

The rise of MAX phase alloys – large-scale theoretical screening for the prediction of chemical order and disorder

“…This has traditionally been realized through the formation of a solid solution upon metal alloying, resulting in MAX phases with disorder on the metal sites. 8,43–48 This, in turn, can facilitate the derivation of a solid-solution MXene. A recent example is MXene alloys based on Ti, Nb, and/or V at the M-site, for which the electrical conductivity can be controllably varied over three orders of magnitude at room temperature and six orders of magnitude from 10 to 300 K. 49…”

“…Another approach includes elemental substitution in known crystal structures or through solid solution alloying. 5–10…”

“…, i-MAX phases. 7,8,44,45,51 In this work, we focus on metal alloying in 211 MAX phases and systematically investigate the formation of chemical order and solid solution of M′ and M′′, where M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, and Ni, combined with A = Al, Ga, In, Si, Ge, Sn, Ni, Cu, Zn, Pd, Ag, Pt, and Au, and X = C. We combine a large number of chemically ordered structures with high-throughput thermodynamic phase stability predictions and correlate our results to already synthesized quaternary MAX phases, both chemically ordered and disordered (solid solutions). This facilitates a base from which we propose guidelines for which MAX phase compositions can be expected to be chemically ordered or in solid solution.…”

Theoretical Prediction of Two-Dimensional Metal Boride Mg4B6 as a High-Capacity Electrode Material for Lithium-Ion Batteries

“…9 Different from the conventional ternary MAX phases, quaternary (M1 2/3 M2 1/3 ) 2 AlC phases have displayed chemically ordered structures. 10,11 Removal of M2 and Al elements by selective etching can result in the 2D i-MXenes with ordered metal vacancies. For example, Mo 1.33 C 12 and W 1.33 C 13,14 can be obtained by removing Sc and Al from (Mo 2/3 Sc 1/3 ) 2 AlC and (W 2/3 Sc 1/3 ) 2 AlC.…”

312 MAX Phases: Elastic Properties and Lithiation

“…Regarding their mechanical behavior, MAX phases are machinable and have high thermal and damage resistance [11,12]. These properties have constituted the 312 MAX phases as important materials for numerous high-end applications, including space, electronic, and nuclear [13][14][15][16][17][18][19][20][21][22][23][24][25].…”