High temperature healing of Ti2AlC: On the origin of inhomogeneous oxide scale

Yang, H.J.; Pei, Yu; Rao, Jiancun; Hosson, J.Th.M. De; Li, S. B.; Song, Guanyu

doi:10.1016/j.scriptamat.2011.03.031

Cited by 90 publications

(75 citation statements)

References 18 publications

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“…The formation temperature of A containing oxides was found to depend on the bonding strength and stability of MAX phases. While oxidation temperatures of 1100-1200 ℃ were reported for preferred oxidation of Al forming hard, strong and protective Al 2 O 3 layer on Ti 3 AlC 2 and Ti 2 AlC [68,80,[128][129][130] lower oxidation temperatures < 1000 ℃ might be expected by substituting with an A-element of lower bonding energy than Al. M n+1 AX n phases with A being a low melting metal (A = Ga, In) were recently reported to exhibit unusual physical phenomena based on deintercalation of the A element [131].…”

Section: Enhanced Reactivity Of Repair Fillersmentioning

confidence: 99%

Generic principles of crack-healing ceramics

Greil

2012

J Adv Ceram

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Abstract:Ceramic materials able to heal manufacture or damage induced microstructure defects might trigger a change in paradigm for design and application of load bearing ceramics. This work reviews thermodynamic and kinetic aspects governing the regeneration of solid contact able to transfer stress between disrupted crack surfaces in ceramics. Major crack healing processes include perturbation of crack-like pores followed by sintering of isolated pores, as well as reaction with an environmental atmosphere and filling of the crack space with an oxidation product. Since thermally activated solid state reactions require elevated temperatures which may exceed 1000 ℃, processes able to trigger crack healing at lower temperatures are of particular interest for transferring into engineering applications. Generic principles of microstructure modifications able to facilitate crack repair at lower temperatures will be considered: (i) acceleration of material transport by grain boundary decoration and grain size reduction, and (ii) reduction of thermal activation barrier by repair filler activation. Examples demonstrating crack healing capability include oxidation reaction of low energy bonded intercalation metal from nano-laminate MAX phases and catalyzed surface nitridation of polymer derived ceramics containing repair fillers.

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Section: Enhanced Reactivity Of Repair Fillersmentioning

confidence: 99%

Generic principles of crack-healing ceramics

Greil

2012

J Adv Ceram

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“…They are nanolamellas with M n+1 AX n (n is 1, 2, or 3) chemical formula, where M is an early transition metal, A is an A-group element from the periodic table and X is either carbon or nitrogen [1]. These compounds are known for their low density [1], high stiffness [2,3], superior thermal shock resistance [1,4], damage tolerance [5,6], self-healing behavior [7,8], significant electrical conductivity [4,9], and erosion [10], oxidation [11][12][13][14][15][16] and hot corrosion resistance [6,17]. Moreover, M n+1 AX n phases have been identified as promising candidates for hydrogen storage applications [18] along with other materials [19,20].…”

Section: Introductionmentioning

confidence: 99%

Sputtering Power Effects on Growth and Mechanical Properties of Cr2AlC MAX Phase Coatings

Naveed

Obrosov

Żak

et al. 2016

Metals

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Abstract:Coating growth and mechanical properties of nanolamellar Cr 2 AlC coatings at various sputtering power were investigated in the present study. Cr 2 AlC coating was deposited on the IN 718 superalloy and (100) Si wafers by DC magnetron sputtering at different sputtering powers. The structure and properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. It was found that coatings had columnar structure with nanocrystalline substructure. Deposition rate increased with the sputtering power. XRD results showed the presence of the Cr 2 AlC MAX phase, intermetallic AlCr 2 and Cr 7 C 3 carbide phases, along with the change in preferential coating growth orientation. TEM observations confirmed the occurrence of these phases, and the SAED patterns demonstrated significant texture of the coatings. Hardness values were measured in the range between 11-14 GPa, showing a slight increase with the sputtering power.

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“…The minimum temperature for formation of such a continuous protective layer is at least 700 °C [15]. During growth of the α-Al 2 O 3 layer, TiO 2 forms on top of the Al 2 O 3 scale as a result of Ti diffusion through the Al 2 O 3 layer to the surface where it reacts with oxygen [16,17]. Once the α-Al 2 O 3 has grown to sufficient thickness, it will protect against further oxidation of the underlying Ti 2 AlC on the condition that the latter is sufficiently phase-pure [18,19,20].…”

Section: Introductionmentioning

confidence: 99%

Phase stability and initial low-temperature oxidation mechanism of Ti2AlC thin films

Frodelius

Jensen

et al. 2013

Journal of the European Ceramic Society

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Ti2AlC thin films deposited onto Al2O3 by magnetron sputtering were used as model for studying the early stages (andlt; 15 min) of relatively low-temperature (500 degrees C) oxidation of Ti2AlC. The well-defined microstructure of these films forms a surface of valleys, hillocks and plateaus comprised of basal-plane-oriented grains with a fraction of nonbasal-plane-oriented grains with out-of-plane orientation of (1 0 (1) over bar 3) and (1 0 (1) over bar 6) as shown by X-ray diffraction and s electron microscopy. During oxidation, Al2O3 clusters and areas of C-containing titania (TiOxCy) are formed on the surface. A mechanism is proposed in which the locations of the Al2O3 clusters are related to the migration of Al atoms diffusing out of Ti2AlC. The Al2O3 is initially formed in valleys or on plateaus where Al atoms have been trapped while TiOxCy forms by in-diffusion of oxygen into the Al-deficient Ti2AlC. At 500 degrees C, the migration of Al atoms is faster than the oxidation kinetics; explaining this microstructure-dependent oxidation mechanism.

Funding Agencies|Swedish National Graduate School in Materials Science||

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High temperature healing of Ti2AlC: On the origin of inhomogeneous oxide scale

Cited by 90 publications

References 18 publications

Generic principles of crack-healing ceramics

Generic principles of crack-healing ceramics

Sputtering Power Effects on Growth and Mechanical Properties of Cr2AlC MAX Phase Coatings

Phase stability and initial low-temperature oxidation mechanism of Ti2AlC thin films

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