Evidence of α-nanophase heterogeneous nucleation from ω particles in a β-metastable Ti-based alloy by high-resolution electron microscopy

Prima, Frédéric; Vermaut, P.; Texier, G.; Ansel, D.; Gloriant, T.

doi:10.1016/j.scriptamat.2005.10.024

Cited by 219 publications

(111 citation statements)

References 11 publications

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“…The evolution of electrical resistivity in this alloy that undergoes similar consequent phase transitions is further discussed using more direct methods as transmission electron microscopy (TEM), X-ray diraction (XRD) and neutron-diraction [9,11,12]. Very similar Ti12Mo alloy was investigated in [13].…”

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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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confidence: 99%

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

et al. 2015

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“…It is reported that the w lattice is obtained by the collapse of one pair of (111) [36][37][38]. A transmission electron microscopy investigation of Ti-(18-22)V [wt.%] alloys revealed that the intensities of the w reflections in the Ti-20 V alloy were much weaker than those in Ti-18 V alloy, and the w reflections in the Ti-22 V alloy disappeared, suggesting that formation of the w phase becomes difficult as the stability of the b phase increases [39].…”

Section: Resultsmentioning

confidence: 99%

Microstructures and mechanical properties of as‐cast titanium–zirconium–molybdenum ternary alloys

Yang

Wang

Shi

et al. 2018

Materialwissenschaft Werkst

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In this study titanium-zirconium-molybdenum alloys (Ti 50 Zr 50 ) 100-x Mo x (xMo; x = 0 at.%, 1 at.%, 3 at.%, 5 at.% or 7 at.%) were investigated, focusing on the effect of molybdenum addition on their microstructures and mechanical properties. Transmission electron microscopy observations revealed that the binary Ti 50 Zr 50 alloy was composed entirely of an acicular hexagonal structure of the a' phase. When the molybdenum content was 1 at.%, the alloy was composed of b and w phases. However, when 3 at.% or more molybdenum was added, only the equiaxed, retained b phase was observed. Tensile tests at room temperature indicated that the mechanical properties of the 1Mo alloy were inferior owing to the embrittlement effects of the w phase and the difficulty of dislocation motion through the w phase. Our research suggested that the 5Mo alloy had excellent ductility (16.5 %) as well as adequate strength (780 MPa). The improved mechanical properties were attributed to the enhanced stability of the b phase and the disappearance of the w phase.

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“…Precipitation of α phase is so important that a great deal of research has been conducted on processing and heat treatments that can control precipitation [3][4][5][6][7][8] . In the literature, it has been reported that precipitation of α phase is affected by transition phases (ω phase 9,10) , β ′ phase 11,12) ) and dislocation 13,14) . The α phase, when it is nucleated at a transition phase, is more re ned than when it is not nucleated in the transition phase [9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

“…In the literature, it has been reported that precipitation of α phase is affected by transition phases (ω phase 9,10) , β ′ phase 11,12) ) and dislocation 13,14) . The α phase, when it is nucleated at a transition phase, is more re ned than when it is not nucleated in the transition phase [9][10][11][12] . ω phase precipitates in TIMETAL ® LCB (Ti-6.8Mo-4.5Fe-1.5Al(mass%)), which is one of the metastable β titanium alloys 15,16) .…”

Section: Introductionmentioning

confidence: 99%

“…ω phase precipitates in TIMETAL ® LCB (Ti-6.8Mo-4.5Fe-1.5Al(mass%)), which is one of the metastable β titanium alloys 15,16) . It was reported that a re ned α phase precipitated at ω phase in Ti-6.8Mo-4.5Fe-1.5Al 9) . On the other hand, our group reported that two-step aging, which consists of the rst aging at 300 C, followed by the second aging at 500 C, promoted α phase precipitation and re ned the α phase.…”

Section: Introductionmentioning

confidence: 99%

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Effects of α Phase Nucleating at Transition Phase and Dislocation on Mechanical Properties in Metastable β Titanium Alloy Ti-6.8Mo-4.5Fe-1.5Al

et al. 2017

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Effects of α phase nucleating at a transition phase and dislocation on mechanical properties in a metastable β titanium alloy, Ti-6.8Mo-4.5Fe-1.5Al(mass%), were investigated. Tensile test and optical, scanning, and transmission electron microscopy were used. Two-step aging promoted the precipitation of a ne α phase in grain interiors because the α phase nucleated at a transition phase of β ′ . A precipitation-free zone appeared at rst, but nally disappeared during aging. A specimen that included the precipitation-free zone showed lower yield strength and larger elongation than it did without the precipitation-free zone. This was because dislocation could easily glide in the precipitation-free zone, which was veri ed from examination of the intergranular ductile fracture surface. The transition phase of β ′ promoted the disappearance of a precipitation-free zone, due to the promotion of α phase precipitation, resulting in enhancement of yield strength and deterioration of elongation. It is likely that the width of PFZ and the crystallographic orientation of β grains determine fracture mode to be intergranular ductile, intergranular brittle or intragranular fractures. Aging after tensile deformation produced α phase precipitation at dislocation. A speci c variant of α phase was selected due to a stress eld around the dislocation that included a planar slip band. This resulted in the formation of a large colony of the speci c α variant, while elongation deteriorated because the large colony probably facilitated crack propagation.

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Evidence of α-nanophase heterogeneous nucleation from ω particles in a β-metastable Ti-based alloy by high-resolution electron microscopy

Cited by 219 publications

References 11 publications

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

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

Microstructures and mechanical properties of as‐cast titanium–zirconium–molybdenum ternary alloys

Effects of α Phase Nucleating at Transition Phase and Dislocation on Mechanical Properties in Metastable β Titanium Alloy Ti-6.8Mo-4.5Fe-1.5Al

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