Precipitation behavior of Widmanstätten O phase associated with interface in aged Ti2AlNb-based alloys

Cai, Qi; Li, Mengchen; Zhang, Yaran; Liu, Yongchang; Ma, Zongqing; Li, Chong; Li, Huijun

doi:10.1016/j.matchar.2018.09.009

Cited by 30 publications

(5 citation statements)

References 37 publications

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“…The oxidation process of Ti 2 AlNb alloys is controlled by the microstructure of the initial B2-O two-phase interface, and the extremely lamellar morphology restricts the diffusion of oxygen [13]. In our previous experiments on the oxidation mechanisms of Ti 2 AlNb alloys at 800 • C, the TEM observations revealed that the O phase and B2 phase followed a crystallographic-orientation relationship of [111]B2//[110]O and (110)B2//(001)O [14], which was also observed in other studies related to Ti 2 AlNb alloys [15,16].…”

Section: Introductionsupporting

confidence: 79%

First-Principles Investigation on the Adsorption and Diffusion of Oxygen at the B2(110)–O(001) Interface in Ti2AlNb Alloys

Zhang,

Xiang,

et al. 2024

Metals

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The adsorption and diffusion of oxygen at the B2(110)[1¯11]||O(001)[11¯0] interface in Ti2AlNb alloys were investigated via first-principles calculations. Only a 2.6% interfacial mismatch indicates that B2(110)–O(001) is basically a stable coherent interface. The calculated adsorption energies and diffusion energy barriers show that oxygen prefers to occupy the Ti-rich interstitial sites, and once trapped, it hardly diffuses to other interstitial sites, thus promoting the preferential formation of Ti oxides. Under the premise of a Ti-rich environment, a Nb-rich environment is more favorable for oxygen adsorption than an Al-rich environment. The electronic structures suggest that O 2p orbitals mainly occupy the energy region below −5 eV, bonding with its coordinated atoms of Ti, Al, and Nb. However, Al 3p and Nb 4d orbitals near the Fermi level couple with sparsely distributed O 2p orbitals, forming anti-bonding, which is not conducive to oxygen adsorption. Because Nb 4d electrons are more localized than Al 3p electrons are, Nb–O anti-bonding is weaker. O–Ti has almost no contribution to anti-bonding, suggesting good bonding between them. This is consistent with the experimental observations that TiO2 is the main oxidation product.

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Section: Introductionsupporting

confidence: 79%

First-Principles Investigation on the Adsorption and Diffusion of Oxygen at the B2(110)–O(001) Interface in Ti2AlNb Alloys

Zhang,

Xiang,

et al. 2024

Metals

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“…After that, the samples were held for 0.5 h, 1 h, 1.5 h, and 2 h, respectively, and were then water-quenched to room temperature. alloys have attracted intensive attention in the past two decades due to their superior mechanical properties [10][11][12]. Wang et al reported that after thermomechanical processing followed by solid solution and aging at the B2 + O region, a lamellar microstructure was obtained which exhibited excellent tensile strength at room and elevated temperatures [13][14][15].…”

Section: Methodsmentioning

confidence: 99%

“…Although the alloys with a single O phase were found to have poor room-temperature ductility and toughness, the O phase as a second phase has a positive effect on the mechanical properties. Therefore, the dual-phase (O + B2) Ti 2 AlNb alloys have attracted intensive attention in the past two decades due to their superior mechanical properties [10][11][12]. Wang et al reported that after thermomechanical processing followed by solid solution and aging at the B2 + O region, a lamellar microstructure was obtained which exhibited excellent tensile strength at room and elevated temperatures [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Precipitation Behavior of Orthorhombic Phase in Ti-22Al-25Nb Alloy during Slow Cooling Aging Treatment and Its Effect on Tensile Properties

Wei

Tang

Chen

et al. 2020

Metals

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The precipitation behavior of the orthorhombic (O) phase during the slow cooling aging treatment of Ti-22Al-25Nb (at.%) alloy was investigated by microstructural characterization. Then the effect of O phase precipitation on the tensile properties was studied by room-temperature tensile tests. The results showed that the precipitation of the O phase transformed from both grain boundaries and intragranular to only grain boundaries with the temperature increasing. The nucleation mechanism of the O phase from intergranular is composed of sympathetic nucleation and interface instability nucleation. In addition, the results of tensile tests indicated that the ultimate tensile strength of the alloy decreases as the precipitation of the O phase increases. Meanwhile, from the tensile results, it is concluded that the optimum heat treatment process is slow cooling after aging at 950 °C for 1 h.

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“…As a result, powder metallurgy, a near-net-shape technique, was employed to fabricate uniform and shaped Ti-22Al-25Nb components by researchers. Among the common powder metallurgy methods, spark plasma sintering (SPS) and hot isostatic pressing (HIP) have been widely used to prepare Ti-22Al-25Nb and Ti-22Al-24Nb-0.5Mo (at.%) alloys [8][9][10]. These two methods are both pressure-assisted.…”

Section: Introductionmentioning

confidence: 99%

Precipitation behavior of Widmanstätten O phase associated with interface in aged Ti2AlNb-based alloys

Cited by 30 publications

References 37 publications

First-Principles Investigation on the Adsorption and Diffusion of Oxygen at the B2(110)–O(001) Interface in Ti2AlNb Alloys

First-Principles Investigation on the Adsorption and Diffusion of Oxygen at the B2(110)–O(001) Interface in Ti2AlNb Alloys

Precipitation Behavior of Orthorhombic Phase in Ti-22Al-25Nb Alloy during Slow Cooling Aging Treatment and Its Effect on Tensile Properties

In situ investigation on densification mechanism of Ti-20Al-19Nb (at.%) alloy by TiH2-assisted pressureless sintering

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