Synthesis of MAX Phases in the Hf–Al–C System

Lapauw, Thomas; Tunca, Bensu; Cabioc’h, Thierry; Lu, Jun; Persson, Per O. Å.; Lambrinou, Konstantina; Zhang, Fei

doi:10.1021/acs.inorgchem.6b01398

Cited by 71 publications

(53 citation statements)

References 33 publications

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“…MAX phases in the Zr-Al-C and Hf-Al-C systems combine a large M-atom with a small A-atom. They have been only recently experimentally synthesised 9,36,37 , always in combination with MC binary carbides and never as phase-pure bulk compounds. This might be associated with the aforementioned steric effect and their outlier positions in Fig.…”

Section: Discussionmentioning

confidence: 99%

The double solid solution (Zr, Nb)2(Al, Sn)C MAX phase: a steric stability approach

Lapauw

Tunca

Potashnikov

et al. 2018

Sci Rep

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The addition of Nb and Sn to Zr2AlC is investigated, targeting the synthesis of a Zr-rich bulk MAX phase free of ZrC. The 211 phase formation in the two quaternary Zr-Nb-Al-C and Zr-Al-Sn-C systems is evaluated. Solubility over the entire compositional range in (Zr, Nb)2AlC and Zr2(Al, Sn)C is observed. In terms of effectiveness, the addition of Sn is preferred over the addition of Nb, as the former is selectively incorporated into the 211 structure. A combinatorial approach results in the formation of phase-pure (Zr0.8, Nb0.2)2(Al0.5, Sn0.5)C. The effect of the added solutes on the microstructure and crystallographic parameters is investigated. The addition of Nb and Sn reduces the distortion parameter of the trigonal prism compared to pure Zr2AlC. Therefore, an attempt is made to establish a more general stability criterion for the M2AC structure based on the steric relationship between the atoms in the M6A trigonal prism. Inspired by the Hume-Rothery rules, it is suggested that comparable atomic radii of the M- and A-atoms provide a good starting point to obtain a stable 211 MAX phase.

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Section: Discussionmentioning

confidence: 99%

The double solid solution (Zr, Nb)2(Al, Sn)C MAX phase: a steric stability approach

Lapauw

Tunca

Potashnikov

et al. 2018

Sci Rep

Self Cite

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“…The second ratio, 3:1.01:1.8, gives both MAX phases, but there are more Hf 3 AlC 2 than Hf 2 AlC. For this product containing the two MAX phases, amounts of the compounds are given as 46% by weight of HfC, 33% Hf 3 AlC 2 , 16% Hf 2 AlC, and 5% HfAl 2 …”

Section: Resultsmentioning

confidence: 99%

“…The holding time is 30 min. When starting the HP, the pressure applied is 7 MPa until the desired temperature is reached and then increasing the pressure to 30 MPa …”

Section: Phasesmentioning

confidence: 99%

“…When starting the HP, the pressure applied is 7 MPa until the desired temperature is reached and then increasing the pressure to 30 MPa. [37] Other attempts were made by HP using as reactant Hf, Al, and graphite. They were mixed in a ratio of Hf:Al:C = 2:2.1:3.9, ball-milled for 24 h in absolute alcohol, then dried and HPed under a pressure of 30 MPa and an Ar flow for 1 h at 1900 °C.…”

Section: Hot-pressingmentioning

confidence: 99%

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Synthesis Protocols of the Most Common Layered Carbide and Nitride MAX Phases

2020

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MAX phases represent a large group of carbide‐ and nitride‐layered ternary compounds. Their general formula is Mn+1AXn, where n = 1–3, M is an early transition metal, A is an A‐group element, and X is either carbon or nitrogen. The MAX phases combine properties of metals (good electrical and thermal conductivity, machinability, low hardness, thermal shock resistance, and damage tolerance) with those of ceramics (high elastic moduli, temperature strength, and oxidation and corrosion resistance). Publications on MAX phases have increased considerably in recent years. A late development causing heightened interest in MAX phases is the possibility by which these can be selectively etched to MXenes by removal of the A‐group element. In view of optimizing properties for prospective applications, the synthesis protocols of some of the most common carbide and nitride MAX phases are reviewed. Characterization of their physical, mechanical, and corrosion/oxidation properties is also discussed. Recent developments have revealed the potential for further practical application and have led to accessible strategies to synthesize new MAX phases using the pressure‐less sintering, spark plasma sintering, or molten salt routes.

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“…This creates difficulties in producing MAX phases in above systems, which explains the scarcity of the experimental works despite of their relatively late discovery, and the high amount of impurity phases in the samples [62,63,173].…”

Section: Inherently Nanolaminated Carbidesmentioning

confidence: 99%

Phase Formation of Nanolaminated Transition Metal Carbide Thin Films

Lai¹

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The cover image is a simple sketch of structural-chemical relation in between the metal layers in nanolaminated transition metal carbides: Mo2GaC, Mo2Ga2C, and Mo2(Au1-xGax)2C with an in-plane order in the Au-Ga layers, where the last two phases were discovered in this thesis. © Chung-Chuan Lai 2017Printed in Sweden by LiU-Tryck 2017 ISSN 0345-7524 ISBN 978-91-7685-526-3 i AbstractResearch on inherently nanolaminated transition metal carbides is inspired by their unique properties combining metals and ceramics, such as higher damage tolerance, better machinability and lower brittleness compared to the binary counterparts, yet retaining the metallic conductivity. The interesting properties are related to their laminated structure, composed of transition-metal carbide layers interleaved by non-transition-metal (carbide) layers. These materials in thin-film form are particularly interesting for potential applications such as protective coatings and electrical contacts. The goal of this work is to explore nanolaminated transition metal carbides from the aspects of phase formation and crystal growth during thin-film synthesis. This was realized by studying phases in select material systems synthesized from two major approaches, namely, from direct-deposition and post-deposition treatment.The first approach was used in studies on the Mo-Ga-C and Zr-Al-C systems. In the former system, intriguing properties have been predicted for the 3D phases and their 2D derivatives (so called MXenes), while in the latter system, the phases are interesting for nuclear applications.In this work, the discovery of a new Mo-based nanolaminated ternary carbide, Mo2Ga2C, is evidenced from thin-film and bulk processes. Its structure was determined using theoretical and experimental techniques, showing that Mo2Ga2C has Ga double-layers in simple hexagonal stacking between adjacent Mo2C layers, and therefore is structurally very similar to Mo2GaC, except for the additional Ga layers. For the Zr-Al-C system, the optimization of phase composition and structure of Zr2Al3C4 in a thin-film deposition process was studied by evaluating the effect of deposition parameters. I concluded that the formation of Zr2Al3C4 is favored with a plasma flux overstoichiometric in Al, and with a minimum lattice-mismatch to the substrates. Consequently, epitaxial Zr2Al3C4 thin film of high quality were deposited on 4H-SiC(001) substrates at 800 °C.With the approach of post-deposition treatment, the studies were focused on a new method of thermally-induced selective substitution reaction of Au for the non-transition-metal layers in nanolaminated carbides. Here, the reaction mechanism has been explored in Al-containing (Ti2AlC and Ti3AlC2) and Ga-containing (Mo2GaC and Mo2Ga2C) phases. The Al and Ga in ii these phases were selectively replaced by Au while the carbide layers remained intact, resulting in the formation of new layered phases, Ti2Au2C, Ti3Au2C2, Mo2AuC, and Mo2(Au1-xGax)2C, respectively. The substitution reaction was explained by fast outward diffus...

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Synthesis of MAX Phases in the Hf–Al–C System

Cited by 71 publications

References 33 publications

The double solid solution (Zr, Nb)2(Al, Sn)C MAX phase: a steric stability approach

The double solid solution (Zr, Nb)2(Al, Sn)C MAX phase: a steric stability approach

Synthesis Protocols of the Most Common Layered Carbide and Nitride MAX Phases

Phase Formation of Nanolaminated Transition Metal Carbide Thin Films

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