Ultra-fast synthesis and thermodynamic analysis of MoAlB by self-propagating high-temperature combustion synthesis

Abstract

MoAlB as a typical member of MAB phases has attracted much-growing attention due to its unique properties. However, the low production of MoAlB powders limits its further development and potential applications. In the present work, the ultra-fast preparation of high-purity MoAlB powders in a few seconds is achieved by self-propagating high-temperature synthesis (SHS) using a raw powder mixture at an atomic ratio of Mo : Al : B = 1 : 1.3 : 1. SHS reaction mechanism is obtained by analyzing the corresponding composition changes of starting materials. Furthermore, the thermodynamic prediction for the SHS reaction is consistent with the present experiments, where the preparation of MoAlB also conforms to two common self-propagating conditions of the SHS. The enthalpy vs. temperature curve shows that the adiabatic temperature of the reaction decreases with the amount of excuse Al increasing but increases when pre-heating the reactants. Also, this thermodynamic calculation provides a new idea for the preparation of other MAB phases by the SHS.

Improving the density functional theory prediction accuracy for elastic moduli and thermal expansion of MoAlB, Fe2AlB2, and Mn2AlB2

“…Recently, the ternary layered borides MAB phases, 1 as a result of inserting one/two Al layers into the binary borides, have attracted much attention because of their unique combination of ceramic and metal-like properties [2][3][4][5] in line with the well-established MAX phases. [6][7][8] In particular, their high fracture toughness, 9 high damage tolerance, 10 and oxidation resistance 11,12 indicate the great potential for high-temperature structural applications.…”

“…33 In 2015, Ade and Hillebrecht named these ternary layered transition-metal borides "MAB phases" after synthesizing and characterizing some single crystals of Cr 2 AlB 2 , Cr 3 AlB 4 , and Cr 4 AlB 6 . 4 In 2016, Kota et al 10 succeeded in the fabrication and characterization of dense polycrystalline MoAlB, and more importantly demonstrated its potential applications for high-temperature structures because of high phase stability, 34 damage tolerance, and excellent oxidation resistance up to 1300 • C, originating from their layered structure, and significantly weaker Al-Al bonds. 28 Recently, the high fracture toughness (5.4 ± 0.2 MPa⋅m 1/2 ), high work of fracture (117 ± 13 J/m 2 ), damage tolerance, and more interesting non-catastrophic failure behavior were indeed observed in Fe 2 AlB 2 after the successful fabrication of dense polycrystalline bulk.…”

“…in 2013, where Fe 2 AlB 2 was found to be a prospective magnetocaloric material 33 . In 2015, Ade and Hillebrecht named these ternary layered transition‐metal borides “MAB phases” after synthesizing and characterizing some single crystals of Cr 2 AlB 2 , Cr 3 AlB 4 , and Cr 4 AlB 6 4 . In 2016, Kota et al 10 .…”

Ternary layered boride MoAlB: A novel thermo-regulation microwave absorbing ceramic material

“…The MAB phase, analogous to MAX, represents a promising group of alternatives where M stands for a transition metal, A typically denotes Al, and B is boron. The laminated crystal structures of the MAB phase consist of M-B (transition metal boride) layers interspersed with layers of Al [28]. Therefore, the MAB phase possesses both metallic and ceramic properties, offering intriguing attributes such as good electrical, thermal, and mechanical properties, as well as chemical and thermal stability.…”

“…Therefore, the MAB phase possesses both metallic and ceramic properties, offering intriguing attributes such as good electrical, thermal, and mechanical properties, as well as chemical and thermal stability. Since MoAlB was rediscovered by Kota et al [28] in 2016, an increasing number of MAB phase ceramics, including MoAlB [29], WAlB [30], Fe 2 AlB 2 [31], Cr 2 AlB 2 [32], Cr 4 AlB 6 [32], Cr 3 AlB 4 [32], Cr 4 AlB 4 [32], Mn 2 AlB 2 [33], and Ti 2 InB 2 [34], have attracted increasing attention of researchers. Their properties have also been studied by an increasing number of researchers.…”