In situ surface analytical investigation of the thermal oxidation of Ti–Al intermetallics up to 1000 °C

Kovács, Krisztina; Perczel, I.V.; Josepovits, V.K.; Kiss, G.; Réti, F.; Deák, Péter

doi:10.1016/s0169-4332(02)00875-9

Cited by 38 publications

(22 citation statements)

References 18 publications

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“…4) However, the poor ductility and fracture toughness at ambient temperatures are the major obstacles for the practical use of these materials. 5,6) Among the variety of attempts to overcome the problems, such as grain refinement, chemistry modification, microstructure control and composite formation, synthesizing of composite seems to be a promising approach, which can not only resolve the problem of poor ductility and toughness at ambient temperatures, but also provide the right combination of high-temperature strength and creep resistance. 4,7) Among various intermetallics, the compound of Ti 5 Si 3 has been considered as a promising material for high-temperature structural applications, in view of its high melting temperature (2 403 K), low density (4.32 g/cm 3 ), high hardness (1 130 HV), and high oxidation resistance.…”

Section: Introductionmentioning

confidence: 99%

“…5,6) Among the variety of attempts to overcome the problems, such as grain refinement, chemistry modification, microstructure control and composite formation, synthesizing of composite seems to be a promising approach, which can not only resolve the problem of poor ductility and toughness at ambient temperatures, but also provide the right combination of high-temperature strength and creep resistance. 4,7) Among various intermetallics, the compound of Ti 5 Si 3 has been considered as a promising material for high-temperature structural applications, in view of its high melting temperature (2 403 K), low density (4.32 g/cm 3 ), high hardness (1 130 HV), and high oxidation resistance. [2][3][4]7,8) Moreover, the Ti 5 Si 3 has also been identified as a compatible and thermochemically stable reinforcing phase for TiAl matrix, and Ti 5 Si 3 -TiAl composites have been the subject of numerous researches as potential structure materials for hightemperature applications.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4]7,8) Moreover, the Ti 5 Si 3 has also been identified as a compatible and thermochemically stable reinforcing phase for TiAl matrix, and Ti 5 Si 3 -TiAl composites have been the subject of numerous researches as potential structure materials for hightemperature applications. 4,[5][6][7][8][9] Recently, fabrication of in situ composites of TiAl with 5-20 vol% Ti 5 Si 3 was conducted by reactive sintering of elemental powder compacts. 7) As reported by Alman, 7) the addition of Si is beneficial to densification during reactive sintering of TiAl, and the simultaneous formation of TiAl and Ti 5 Si 3 tends to eliminate the Kirkendal porosity.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental observations show that the addition of Si in the Ti-Al powder mixture enhances the sustainability of the reaction and the increase of Ti 5 Si 3 formed in the composite increases the combustion temperature and combustion wave velocity. 4) While so many efforts were devoted to Ti 5 Si 3 and TiAl monolithic and/or composite in the previous works, 4,[5][6][7][8][9][10] only a few focused on Ti 5 Si 3 -TiAl 3 composites. As is known, intermetallic compound of TiAl 3 bears many attractive characteristics such as very low density (3.37 g/cm 3 ), relatively high hardness (660-750 HV), good oxidation and heat resistance, as well as moderately high melting temperature (1 623 K), 11) which are also cited as merits for potential low density high-temperature structure materials.…”

Section: Introductionmentioning

confidence: 99%

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Self-propagating High-temperature Synthesis of Ti5Si3/TiAl3 Intermetallics

Zha

Wang

et al. 2009

ISIJ Int.

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The products with designed volume ratio of Ti 5 Si 3 : TiAl 3 ϭ1 : 0, 3 : 1, 1 : 1, 1 : 3 and 0 : 1 prepared by selfpropagating high-temperature synthesis (SHS) were investigated in the present study. The differential thermal analysis (DTA) results suggested that the Si in reactants had a significant influence not only on the melting of Al, but also on the subsequently exothermic reaction between Ti and Al. Also, the presence of Al altered the reaction process of Ti 5 Si 3 . The phase composition of SHS reaction product agreed well with the designed volume ratio of Ti 5 Si 3 : TiAl 3 . Compared with those apparently coarse ones in monolithic Ti 5 Si 3 or TiAl 3 , the grains were considerably refined and microcracks gradually disappeared in products with coexistence of Ti 5 Si 3 and TiAl 3 .KEY WORDS: intermetallics; combustion synthesis (CS); microstructure; differential thermal analysis. 453© 2009 ISIJ microstructures and improved properties, especially, both the reactions for the reinforcement and matrix formations are exothermic in the preparation of IMCs. 4,10,12,13) Therefore, we conduct an investigation on Ti 5 Si 3 -TiAl 3 system with changing volume ratio of Ti 5 Si 3 : TiAl 3 by SHS process. The study aims to investigate the reaction mechanism, also the phase composition and morphology of final products with changing volume ratio of Ti 5 Si 3 : TiAl 3 . It is expected that the preliminary work could lay a foundation and make a significant promotion in the development of high-temperature structure materials. Experimental ProcedureFive different mixtures of Al, Ti, and Si powders were prepared in order to produce Ti 5 Si 3 -TiAl 3 with varying volume fractions of each phase. The intended final products were designed to contain Ti 5 Si 3 and TiAl 3 with a volume ratio corresponding to 1 : 0, 3 : 1, 1 : 1, 1 : 3 and 0 : 1, respectively. The powders used in the present work were commercial powders of Al (98.0 % purity, ϳ29 mm), Ti (99.5 % purity, ϳ15 mm), and Si (99.5 % purity, ϳ15 mm), respectively. Powder blends with different starting compositions were mixed sufficiently by a ball milling for 6 h with the weight ratio of ball to powder of 2 : 1, and then were cold-isostatically pressed at pressures ranging from 55 to 60 MPa to form cylindrical preforms (22 mm in diameter and 11Ϯ0.5 mm in length) with 70Ϯ9 % theoretical density.The combustion synthesis experiments were carried out under a protective atmosphere of industrial argon (99.9 %). The combustion reaction of the preforms was ignited by heating its bottom surface. The preforms were placed on the graphite-flat which was fixed above a tungsten electrode and ignited by the arc heat. Experiments were performed with preforms without any preheating.Prior to various measurements and characterization, all samples were carefully polished to remove a thin surface layer in order to eliminate the possible oxidation products which might form during combustion synthesis process. The as-combusted compacts were hand-ground with pestle and mortar into fine powders, ...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Self-propagating High-temperature Synthesis of Ti5Si3/TiAl3 Intermetallics

Zha

Wang

et al. 2009

ISIJ Int.

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“…In the presence of excess oxygen TiO oxidizes further to Ti 2 O 3 and to TiO 2 . The increased thermodynamic stability of the different Ti oxides leads to the Ti accumulation at the surface through oxidation driven segregation of the metal components [6]. The in depth distribution profile of oxygen after the 400 o C anneal in Fig.…”

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confidence: 99%