Structural investigation of substoichiometry and solid solution effects in Ti2Al(Cx,N1−x)y compounds

Cabioc’h, Thierry; Eklund, Per; Mauchamp, Vincent; Jaouen, M.

doi:10.1016/j.jeurceramsoc.2011.12.011

Cited by 62 publications

(56 citation statements)

References 32 publications

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“…One possibility, always present, is sample-to-sample variations. Other possibilities are secondary phases and effects of non-stoichiometry, the latter known to occur for several other MAX phases [25,49 ].…”

Section: Discussionmentioning

confidence: 99%

“…2c) is not a general trend in MAX phases even if it is also the case for (Ti 1-x ,V x ) 2 AlC and (V 1-x ,Cr x ) 2 AlC solid solutions [24]. For instance, the a lattice parameter varies linearly as a function of x in Ti 2 Al(C x N 1-x ) [25] but not the c lattice parameter. Neither a nor c vary linearly with x for (Ti 1-x ,Cr x ) 2 AlC compounds [24].…”

Section: It Is Then Assumed That a Random Solid Solution Is Obtained mentioning

confidence: 90%

“…Solid-solution studies have mostly focused on exploring solid solution hardening effects [18,19,20,21,22,23], the evolution of the unit cell structure [24,25] or the possibility to synthesize new MAX phases [26,27,28,29]. Interestingly, with a few possible exceptions [30,31,32], solid solution hardening of the MAX phases does in general not appear to be pronounced.…”

Section: Introductionmentioning

confidence: 99%

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Tailoring of the thermal expansion of Cr2(Alx,Ge1−x)C phases

Cabioc’h¹,

Eklund²,

Mauchamp³

et al. 2013

Journal of the European Ceramic Society

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106

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Section: Discussionmentioning

confidence: 99%

Section: It Is Then Assumed That a Random Solid Solution Is Obtained mentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tailoring of the thermal expansion of Cr2(Alx,Ge1−x)C phases

Cabioc’h¹,

Eklund²,

Mauchamp³

et al. 2013

Journal of the European Ceramic Society

Self Cite

106

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“…The number of X elements is by definition limited by to only C and N but due to their similar chemical bonding characteristics, resembling its binaries MC and MN, they can form a wide range of MAX carbonitride solid solutions [47,48]. This allows investigation on correlations between chemistry and physical properties.…”

Section: Max Phase Alloysmentioning

confidence: 99%

Materials Design from First Principles : stability and magnetism of nanolaminates

Dahlqvist¹

2014

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The front cover image is a close up of M (red and blue spheres) and X (grey sphere) in M 2 AX. In the background its nanolaminated structure consisting of ordered, clustered, and disordered atoms or magnetic moments is illustrated.The spine image shows charge redistribution for an interstitial oxygen atom in Cr 2 AlC where blue indicate gain of electrons and red loss of electrons.The back cover image shows charge redistribution when oxygen substitutes for carbon in Ti 2 AlC where blue indicate gain of electrons and red loss of electrons. My daughter described it as "a planet, with water, and trees, and blue leaves". © Martin Dahlqvist, unless otherwise stated. Printed by LiU-Tryck, Linköping, Sweden, 2014 To my JETs ♥ v ABSTRACT In this thesis, first-principles calculations within density functional theory are presented, with a principal goal to investigate the phase stability of so called M n+1 AX n (MAX) phases. MAX phases are a group of nanolaminated materials comprised of a transition metal (M), a group 12-16 element (A), and carbon or nitrogen (X). They combine ceramic and metallic characteristics, and phase stability studies are motivated by a search for new phases with novel properties, such as magnetism, and for the results to be used as guidance in attempted materials synthesis in the lab.To investigate phase stability of a hypothetical material, a theoretical approach has been developed, where the essential part is to identify the set of most competing phases relative to the material of interest. This approach advance beyond more traditional evaluation of stability, where the energy of formation of the material is generally calculated relative to its single elements, or to a set of ad hoc chosen competing phases. For phase stability predictions to be reliable, validation of previous experimental work is a requirement prior to investigations of new, still hypothetical, materials. It is found that the predictions from the developed theoretical approach are consistent with experimental observations for a large set of MAX phases. The predictive power is thereafter demonstrated for the new phases Nb 2 GeC and Mn 2 GaC, which subsequently have been synthesized as thin films. It should be noted that Mn is used for the first time as sole M-element in a MAX phase. Hence, the theory is successfully used to find new candidates, and to guide experimentalists in their work on novel promising materials. Phase stability is also evaluated for MAX phase alloys. Incorporation of oxygen in different M 2 AlC phases are studied, and the results show that oxygen prefer different sites depending on M-element, through the number of available non-bonding M delectrons. The theory also predicts that oxygen substituting for carbon in Ti 2 AlC stabilizes the material, which explains the experimentally observed 12.5 at% oxygen (x = 0.5) inMagnetism is a recently attained property of MAX phase materials, and a direct result of this Thesis work. We have demonstrated the importance of choice of magnetic spin configuration and elec...

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“…MAX-phases can form isostructural solid solutions by substituting in any sublattice that may cause the material properties improvement [15,16]. For example, reduction of thermal expansion coefficient anisotropy due to solid solution formation leads to the decrease of cracking during thermocycling, etc.…”

Section: Introductionmentioning

confidence: 99%

Presence of Oxygen in Ti-Al-C MAX Phases-Based Materials and their Stability in Oxidizing Environment at Elevated Temperatures

et al. 2018

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The Ti3AlC2-, (Ti,Nb)3AlC2-and Ti2AlC-based materials turned out to be more resistant than Crofer JDA steel in oxidizing atmosphere as 1000 h long tests at 600• C have shown. But the amounts of oxygen absorbed by the materials during testing were different. The Ti2AlC-based material demonstrated the lowest oxygen uptake, (Ti,Nb)3AlC2-based absorbed a somewhat higher amount and the highest amount was absorbed by Ti3AlC2-based material. Scanning electron microscopy and the Auger study witnessed that amounts of oxygen in the MAX phases before the exposure in air were as well different: the approximate stoichiometries of the matrix phases of materials were Ti3.1−3.2AlC2−2.2, Ti1.9−4Nb0.06−0.1AlC1.6−2.2O0.1−1.2 and Ti2.3−3.6AlC1−1.9O0.2−0.6, respectively. The higher amount of oxygen present in the MAX phase structures may be the reason for higher resistance to oxidation during long-term heating in air at elevated temperature. The studied materials demonstrated high stabilities in hydrogen atmosphere as well. The bending strength of the Ti3AlC2-and (Ti,Nb)3AlC2-based materials after keeping at 600• C in air and hydrogen increased by 10-15%, but the highest absolute value of bending strength before and after being kept in air and hydrogen demonstrated the Ti2AlC-based material (about 590 MPa).

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Structural investigation of substoichiometry and solid solution effects in Ti2Al(Cx,N1−x)y compounds

Cited by 62 publications

References 32 publications

Tailoring of the thermal expansion of Cr2(Alx,Ge1−x)C phases

Tailoring of the thermal expansion of Cr2(Alx,Ge1−x)C phases

Materials Design from First Principles : stability and magnetism of nanolaminates

Presence of Oxygen in Ti-Al-C MAX Phases-Based Materials and their Stability in Oxidizing Environment at Elevated Temperatures

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