The formation mechanism of the O phase in a Ti3Al–Nb alloy

Wu, Ying; Yang, Danni; Song, Gui Ming

doi:10.1016/s0966-9795(99)00127-2

Cited by 36 publications

(13 citation statements)

References 6 publications

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“…(2). TEM observation indicated that the microstructure in the as-rolled specimen consists of the primary equiaxed 2 -phase, a considerable amount of B2-phase matrix and fine O-phase formed within the primary 2 grain [14][15][16]. Thus, the observed microstructure in the asrolled specimen represented a typical recrystallized structure after thermo-mechanical treatments.…”

Section: Methodsmentioning

confidence: 88%

“…Most work on the oxidation behavior of Ti 3 Al-based alloys concerns the effect of the alloying elements Nb and Si on improvement of oxidation resistance by surface modification [6][7][8][9][10][11][12], however, the effect of microstructure on the oxidation behavior of 14at.%Nb-containing Ti 3 Al-based alloy is still lacking. The formation mechanism and microstructural development of the O-phase as well as the tensile deformation and fracture behavior of Ti 3 Al-Nb alloy have been previously studied by Wu et al [13][14][15][16]. The purpose of the present study, therefore, is to evaluate the isothermal oxidation behavior of Nb, V and Mocontaining Ti 3 Al-based alloy by focusing on the effect of microstructure on the oxidation resistance.…”

Section: Introductionmentioning

confidence: 92%

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The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

Song¹

2010

TOCORRJ

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Abstract:The isothermal oxidation behavior of Ti-24Al-14Nb-3V-0.5Mo alloy in synthetic air from 700°C to 1000°C was studied. The main emphasis was focused on the effect of microstructure obtained by different processes of melting and hot rolling, i.e. large and duplex of 2 +B2, on the oxidation resistance. Regardless of the microstructure, the overall oxidation process of the specimens exposed at 700°C was dominantly controlled by the beneficial effect of Nb-addition due to the formation of a continuous -Al 2 O 3 layer in the scale. However, both specimens showed poor oxidation resistance above 900°C, especially for the as-rolled specimen, because of higher volume fraction of the 2 -phase. The spallation occurred in both specimens at 1000°C, which was probably relative to the formation of Ti 2 AlN between the thick scale and the substrate except for the TiO 2 and -Al 2 O 3 .

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Section: Methodsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 92%

The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

Song¹

2010

TOCORRJ

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“…Moreover, Ti 3 Al also favored the reduction of the possibility of cracking in the laser-cladded coatings. [16] The size of the Ti-6Al-4V alloy was 10mmÂ10mmÂ10mm. Alloy powders of Ti 3 Al (≥99.5% purity, 50~150mm) and TiB 2 (≥99.5% purity, 150~250mm) were used for the laser cladding.…”

Section: Methodsmentioning

confidence: 99%

Surface modification of titanium alloy with the Ti₃Al + TiB₂/TiN composite coatings

Chen

Cui

et al. 2011

Surface & Interface Analysis

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Laser cladding of the Ti 3 Al+TiB 2 pre-placed alloy powder on the Ti-6Al-4V alloy in nitrogen protective atmosphere can form the Ti 3 Al+TiB 2 /TiN composite coating, which can dramatically improve the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti 3 Al+TiB 2 /TiN composite coatings on the Ti-6Al-4V alloy have been researched by means of X-ray diffraction, SEM and energy dispersive spectrometry. It was found that there is a metallurgical combination between the Ti 3 Al+TiB 2 /TiN composite coating and the substrate. The microhardness of the Ti 3 Al+TiB 2 /TiN composite coatings were 3~4 times higher than that of the Ti-6Al-4V alloy because of the actions of the Ti 3 Al+TiB 2 /TiN hard phases and the grain refinement strengthening. Moreover, the wear mass losses of the Ti 3 Al+TiB 2 /TiN composite coatings were much lower than that of the substrate.

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“…6, the lattice parameters of the basal plane of the α 2 lattice were a=0.564 nm and b=1.000 nm while those of the (001) plane of the O-phase were a=0.587 nm and b= 0.980 nm. Since the dimension of the lattice parameter along the c-axis ([0001] direction) of the α 2 -phase, 0.467 nm, was equal to the c-axis ([001] direction) of the O-lattice, the Ophase can be considered as a pseudo-hexagonal phase with a lattice distortion [24]. Fig.…”

Section: Formation Of O-phase In Wrought Ti 3 Al-based Alloymentioning

confidence: 99%

O-phase and carbides precipitation in intermetallics based on Ti−Al

Hwang

2001

Met. Mater. Int.

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In Ti-Al based intermetallics, precipitates of several ternary phases, such as the orthorhombic O-phase, perovskite P-phase and hexagonal H-phase structures, were experimentally identified during aging. These phases are believed to develop from the matrix of the α 2 -phase as a result of the characteristic diffusion of the alloying elements that involves changes in chemical composition and lattice structure. In this paper, the formation mechanism of these phases was studied in the matrix of Ti-Al-based intermetallic compounds. The O-phase was found to form in the primary equiaxed α 2 grains in multivariant forms and as fine α 2 +O mixtures in Ti-24Al-14Nb-3V-0.5Mo alloy during solution treatment at 1000 o C/1h followed by water quenching and aging at 650 o C and 850 o C. The supersaturation of Nb, the β stabilizer, resulted in a segregation of the Nbrich region and Nb-poor region, incurring the formation of the O-phase as a consequence of the α 2 -phase decomposition. A crystallographic orientation relationship between the α 2 -phase and the O-phase was observed. In Ti-46.6Al-2Mn-1.4Mo-0.3C alloy, P-phase carbides formed mainly at the α 2 /γ interface whereas some Hphase carbides were also found within the γ grain and at prior α grain boundaries. The presence of ledges between the P-phase and α 2 -phase interfaces indicated that the nucleation stage of the P-phase involved an interface-controlled process with a coherency relationship at the interface.

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The formation mechanism of the O phase in a Ti3Al–Nb alloy

Cited by 36 publications

References 6 publications

The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

Surface modification of titanium alloy with the Ti₃Al + TiB₂/TiN composite coatings

O-phase and carbides precipitation in intermetallics based on Ti−Al

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The formation mechanism of the O phase in a Ti3Al–Nb alloy

Cited by 36 publications

References 6 publications

The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

The Isothermal Oxidation Behavior of a Ti3Al-Nb-V-Mo Alloy

Surface modification of titanium alloy with the Ti3Al + TiB2/TiN composite coatings

O-phase and carbides precipitation in intermetallics based on Ti−Al

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Product

Resources

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Surface modification of titanium alloy with the Ti₃Al + TiB₂/TiN composite coatings