Microstructural evolution and age hardening behavior of a new metastable beta Ti–2Al–9.2Mo–2Fe alloy

Li, Cheng Lin; Mi, Xujun; Ye, Wenjun; Song, Haizheng; Lee, Dong‐Geun; Lee, Yong-Tai

doi:10.1016/j.msea.2015.08.028

Cited by 18 publications

(8 citation statements)

References 41 publications

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“…Figure 9 shows the TEM micrograph of the alloy aged at 600 °C for 4 h. The inset of corresponding electron diffraction pattern indicated that there was no spots of ω phase, suggesting that ω phase disappeared after aged at 600 °C for sufficient time. The similar phenomenon has occurred in other β titanium alloys, such as Ti-7Mo-3Nb-3Cr-3Al alloy [30] and Ti-2Al-9.2Mo-2Fe alloy [25]. Their TEM observations indicated that the ω phase disappeared after being heated to 600 °C due to its metastable feature at high temperature.…”

Section: Discussionsupporting

confidence: 75%

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Evolution of Secondary α Phase during Aging Treatment in Novel near β Ti-6Mo-5V-3Al-2Fe Alloy

et al. 2018

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Evolution of secondary α phase during aging treatment of a novel near β titanium alloy Ti-6Mo-5V-3Al-2Fe(wt.%) was studied by OM, SEM, and TEM. Results indicated that size and distribution of secondary α phase were strongly affected by aging temperature and time. Athermal ω phase formed after super-transus solution treatment followed by water quenching, and promoted nucleation of needle-like intragranular α in subsequent aging process. When aged at 480 °C, fine scaled intragranular α with small inter-particle spacing precipitated within β grains and high ultimate tensile strength above 1500 MPa was achieved. When the aging temperature increased, the size and inter-particle spacing of intragranular α increased and made the strength reduce, but the ductility got improved. When aging temperature reached as high as 600 °C, ω phase disappeared and intragranular α coarsened obviously, resulting in serious decrease of strength. While mutually parallel Widmanstätten α laths formed at the vicinity of β grain boundaries and grew into the internal area of β grains, and significant improvement of ductility was achieved. As the aging time increased from 4 h to 16 h at 600 °C, the intragranular α grew slightly and brought about minor change of mechanical properties.

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Section: Discussionsupporting

confidence: 75%

“…Additional quite weaker spots were visible at the 1/3 (121) and 2/3 (121) positions of the β reflection. These additional spots were referred to as the ω phase in β titanium alloy Ti-2Al-9.2Mo-2Fe [25]. The presence of these additional spots was direct evidence of ω precipitates within the β matrix of the as-quenched alloy.…”

Section: Discussionmentioning

confidence: 99%

Evolution of Secondary α Phase during Aging Treatment in Novel near β Ti-6Mo-5V-3Al-2Fe Alloy

et al. 2018

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“…When the sample was solution-treated at 850 • C, the hardness value was near 500 HV, and the hardness value was about 640 HV when solution-treated at 1050 • C. After the hardness value of the sample reached a plateau, it began to show a downward trend, which was mainly attributed to the precipitated α phase becoming thicker and longer with further increases in aging time (Figure 8). Similar results were also observed in previous research regarding Ti-2Al-9.2Mo-2Fe alloy when it was aged at 500-600 • C [46]. This also reflected a relative under-aging, peak aging, and over-aging period.…”

Section: Age-hardening Behaviorsupporting

confidence: 90%

Studies on the β → α Phase Transition Kinetics of Ti–3.5Al–5Mo–4V Alloy under Isothermal Conditions by X-ray Diffraction

Xiang

Tan

et al. 2020

Metals

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The β → α phase transition kinetics of the Ti–3.5Al–5Mo–4V alloy with two different grain sizes was investigated at the isothermal temperature of 500 °C. A method to estimate the function of the precipitate fraction of the α phase with different aging times was developed based on X-ray diffraction analysis. The value of the α precipitate fraction increased sharply at first, then increased slowly with the aging time, and finally reached equilibrium. The value of the α precipitate fraction was higher in the alloy aged for the same time at a higher solution temperature, while the size of the α precipitate was smaller at a higher solution temperature. The β → α phase transition kinetics under isothermal conditions were modeled in the theoretical frame of the Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory. The kinetic parameters of JMAK deduced different transformation mechanisms. The mechanism of the phase transition in the first stage was dominated by mixed transformation mechanisms (homogeneously nucleated and acicular-grown α structure, and grain boundary-nucleated and grown α precipitate), while the second stage was the growth of the fine α precipitate, which was controlled by slow diffusion. As the aging time increased, the hardness of the Ti–3.5Al–5Mo–4V alloy increased sharply. After the hardness of the alloy reached a plateau, it began to decline. The hardness of the alloy was always higher at a higher solution temperature.

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“…No significant difference was found in the microhardness of the two zones, which was around 460 HV, higher than that of the base metal. The order of hardness of the phases appearing in the titanium alloy was followed: ω > α s (secondary α phase) > α p (primary α phase) > β > β (metastable β phase) [31][32][33][34]. A large number of equiaxed metastable β phases formed in the weld zone of the as-welded TC17 LFW joint, reducing the hardness.…”

Section: Experimental Results and Analysismentioning

confidence: 99%

Study of the Microstructure and Fracture Toughness of TC17 Titanium Alloy Linear Friction Welding Joint

Ya-juan

et al. 2019

Metals

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In this paper, the fracture toughness of the thermo-mechanically affected zone (TMAZ) and the weld zone (WZ) of the TC17 titanium alloy linear friction welding joint was studied. The relationship between microstructure and fracture toughness of the joint, as well as the morphologies of the joint microstructure and fracture were investigated. The results indicate that after heat treatment, there was no significant difference in hardness between the WZ and the TMAZ of the joint, which was about 420 HV. However, the microstructures of the different zones of the joint were significantly different. The TMAZ was composed of coarse grains having an internal basket-shaped α phase with an uneven grain size, while the WZ was composed of relatively uniform fine grains and contained a sheet-like α phase. The fracture toughness of the TMAZ was found to be higher than that of the WZ, indicating that the microstructure of the joint had a significant impact on the fracture toughness. In addition, the fracture resistance of the TMAZ with coarser grains and uneven microstructure was better than that of the WZ with fine grains and uniform microstructure.

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Microstructural evolution and age hardening behavior of a new metastable beta Ti–2Al–9.2Mo–2Fe alloy

Cited by 18 publications

References 41 publications

Evolution of Secondary α Phase during Aging Treatment in Novel near β Ti-6Mo-5V-3Al-2Fe Alloy

Evolution of Secondary α Phase during Aging Treatment in Novel near β Ti-6Mo-5V-3Al-2Fe Alloy

Studies on the β → α Phase Transition Kinetics of Ti–3.5Al–5Mo–4V Alloy under Isothermal Conditions by X-ray Diffraction

Study of the Microstructure and Fracture Toughness of TC17 Titanium Alloy Linear Friction Welding Joint

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