Three-dimensional morphology and composition of omega precipitates in a binary titanium–molybdenum alloy

Devaraj, Arun; Williams, R. E. A.; Nag, S.; Srinivasan, Raghavan; Fraser, Hamish L.; Banerjee, Rajarshi

doi:10.1016/j.scriptamat.2009.06.006

Cited by 84 publications

(49 citation statements)

References 15 publications

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“…%) alloy [137]. The bcc β-phase to embryonic ω-phase transformation was recently clarified to occur through a displacive-diffusional process [138][139][140]. These authors demonstrated that the formation of ω-phase-like embryos occurred through competing compositional and structural instabilities arising in the bcc lattice of model binary Ti-Mo alloys during rapid cooling from the high-temperature single β-phase field.…”

Section: Agingmentioning

confidence: 99%

A Review of Metastable Beta Titanium Alloys

Kolli

Devaraj

2018

Metals

494

175

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Abstract:In this article, we provide a broad and extensive review of beta titanium alloys. Beta titanium alloys are an important class of alloys that have found use in demanding applications such as aircraft structures and engines, and orthopedic and orthodontic implants. Their high strength, good corrosion resistance, excellent biocompatibility, and ease of fabrication provide significant advantages compared to other high performance alloys. The body-centered cubic (bcc) β-phase is metastable at temperatures below the beta transus temperature, providing these alloys with a wide range of microstructures and mechanical properties through processing and heat treatment. One attribute important for biomedical applications is the ability to adjust the modulus of elasticity through alloying and altering phase volume fractions. Furthermore, since these alloys are metastable, they experience stress-induced transformations in response to deformation. The attributes of these alloys make them the subject of many recent studies. In addition, researchers are pursuing development of new metastable and near-beta Ti alloys for advanced applications. In this article, we review several important topics of these alloys including phase stability, development history, thermo-mechanical processing and heat treatment, and stress-induced transformations. In addition, we address recent developments in new alloys, phase stability, superelasticity, and additive manufacturing.

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Section: Agingmentioning

confidence: 99%

A Review of Metastable Beta Titanium Alloys

Kolli

Devaraj

2018

Metals

494

175

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“…The main reason is the decreasing volume fraction of semicoherent ω iso particles. This can be caused either due to precipitation of α particles [13] (sometimes referred to as α-nano [10]) or simply by dissolution of ω iso particles back to β matrix due to lower stability of the ω-phase in this temperature range [17].…”

Section: C380mentioning

confidence: 99%

Phase Transformations in Ti-15Mo Investigated by in situ Electrical Resistance

et al. 2015

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In this study phase transformations in metastable beta Ti15Mo alloy were investigated by an in situ electrical resistance measurement in a wide range of temperatures from 196• C to 850• C. Dierent temperature ranges of the evolution of electrical resistance were correlated with underlying phase transformations. In the low temperature range, stage I (from 196• C to 220• C) the decrease of electrical resistance with increasing temperature is caused by the dissolution of ω ath (formed during quenching by athermal shue transformation) which is accompanied by the relaxation of lattice strain, while the diusional assisted growth of ωiso in the range from 220 • C was conrmed by temperature cycling during repeated in situ resistance runs from RT. Pre-ageing of samples at 300• C promotes the formation of ωiso particles. Subsequently, ω ath particles are not created, which is fully consistent with electrical resistance measurements. The presence of ω ath and the orientation relationship between ω and β were identied by the electron diraction.

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“…Although the authors suggested a transformation mechanism, the study did not clearly demonstrate whether the transformation involves martensitic characteristics or concurrent compositional variation of the internally growing a phase from the x phase. Another recent study related to this issue, which also used 3DAP analysis to investigate the element variation in x precipitates in a much simpler Ti-Mo alloy system [9], showed that the concentration of Mo in the x phase is <3% on average, with little variation. This indicates that the environment for the x-to-a phase transformation should be almost diffusionless, which is similar to the situation of the pure Ti of martensitic transformation, only in the reverse sequence.…”

Section: Introductionmentioning

confidence: 99%