Relaxation processes in metastable beta titanium alloys

Sommer, A. W.; Motokura, S.; Ono, Kanji; Buck, O.

doi:10.1016/0001-6160(73)90207-1

Cited by 23 publications

(13 citation statements)

References 9 publications

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“…From this peak analysis, we obtained the activation energy E {111} as small as 0.21-0.23 eV for both as-quenched and aged samples, being in substantial agreement with the previous reports [31,40]. Although the activation energies for the two samples are almost unchanged, the IF peak intensity decreases drastically after aging at 373 K for 72 h (as seen from Figs.…”

Section: Mechanical Relaxation In the Submegahertz Frequency Rangesupporting

confidence: 90%

“…This indicates that the elementary process of the ω transformation is closely related to the IF peak, that is, the regions at which the DI-ω transformation has already been completed cannot contribute to the internal friction. Taking into account the previous studies [40,42,43], it is concluded that the present IF peak is attributed to the elementary process, that is, the "dynamic {111} β collapse" of the ω transformation.…”

Section: Mechanical Relaxation In the Submegahertz Frequency Rangementioning

confidence: 51%

“…Temperature, T (K) where is the relaxation strength, ω r (=2π f r ) the angular frequency, and τ 0 the time constant according to literature [40], τ 0 = 2.2 × 10 −14 s. As indicated by our previous paper [31], such a broad IF profile cannot be correctly reproduced by the Debye function. Therefore, under the condition that ω r τ = ω r τ 0 exp ( E {111} /kT p ) = 1 holds at the peak position, we deduce only the activation energy E {111} by using the 123603-6 following equation:…”

Section: Mechanical Relaxation In the Submegahertz Frequency Rangementioning

confidence: 93%

“…The elementary process of the ω transformation, i.e., the dynamic {111} β collapse, can be detected as a mechanical relaxation by the internal friction (IF) measurement at low temperatures. Since the activation energy of the {111} β collapse is shown to be about 220 meV [40] or 140-180 meV [31], the IF measurement in the submegahertz frequency range must be conducted at low temperatures. Here, the present measurement aims to investigate whether the internal friction is indeed attributed to the dynamic {111} β collapse or not.…”

Section: Mechanical Relaxation In the Submegahertz Frequency Rangementioning

confidence: 99%

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Evolution of microstructure and variations in mechanical properties accompanied with diffusionless isothermal ω transformation in β -titanium alloys

Okamoto

Kasatani

Luckabauer

et al. 2020

Phys. Rev. Materials

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Diffusionless isothermal omega (DI-ω) transformation, which was recently defined in Phys. Rev. Materials 3, 043604 (2019), is classified into a third category of the ω transformation modes, other than the well-known isothermal and athermal modes. This work reveals the characteristic features of the DI-ω transformation in the β-titanium vanadium alloy system, specifically, focusing on variations in the microstructure and mechanical properties with the proceeding of the DI-ω transformation. After quenching alloys of Ti-15at%V, Ti-21at%V, and Ti-27at%V down to below room temperature from the β-stable temperature, in addition to the occurrence of the athermal ω transformation for Ti-15at%V, all of the alloys gradually undergo the DI-ω transformation upon aging at a temperature as low as 373 K, leading to a moderate increase in the hardness. The degree of the hardness increase in these alloys can be successfully explained by a local instability concept based on quenched-in thermal concentration fluctuations. It is also shown that internal friction (Ti-21at%V) diminishes after the low-temperature aging, which indicates the annihilation of such unstable regions showing a dynamic collapse of {111} β pairs to form a transient DI-ω phase. Comparison of inelastic x-ray scattering and ultrasound measurements can see a trail of the DI-ω transformation remaining even in the Ti-27at%V alloy, which has no obvious athermal omega transformation temperature. Based on the results, the difference between athermal ω and DI-ω transformations is finally discussed.

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Section: Mechanical Relaxation In the Submegahertz Frequency Rangesupporting

confidence: 90%

Section: Mechanical Relaxation In the Submegahertz Frequency Rangementioning

confidence: 51%

Section: Mechanical Relaxation In the Submegahertz Frequency Rangementioning

confidence: 93%

Section: Mechanical Relaxation In the Submegahertz Frequency Rangementioning

confidence: 99%

See 2 more Smart Citations

Evolution of microstructure and variations in mechanical properties accompanied with diffusionless isothermal ω transformation in β -titanium alloys

Okamoto

Kasatani

Luckabauer

et al. 2020

Phys. Rev. Materials

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“…It has been established that Tx, the temperature at which the b-x transformation is initiated, decreases rapidly with increasing solute additions. [16] The high solute content of Ti-15-3 alloy and high cooling rates in welding preclude formation of the x phase. [1,17] The strengthening of Ti-15-3 is attributed to the precipitation of uniformly dispersed fine a phase in the b matrix.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of Gas-Tungsten-Arc–Welded Ti-15-3 Beta Titanium Alloy

Balachandar

Sarma

Pant

et al. 2009

Metall Mater Trans A

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Microstructure and mechanical properties of gas-tungsten-arc (GTA)-welded Ti-15V-3Cr-3Sn-3Al alloy in direct current electrode negative mode are characterized. The thermal profile was measured during welding with continuous current (CC) and pulsed current (PC) at different frequencies. A single-step postweld aging of the welded samples at subtransus temperature was attempted to study precipitation of alpha phase. Two different morphologies of alpha phase are observed along with a partitioning of alloying elements into the two phases. Processing conditions for higher strength are identified and correlated with the thermal profile. Microstructure changes due to postweld heat treatment were characterized.

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