Twinning behavior of orthorhombic-α” martensite in a Ti-7.5Mo alloy

Ji, Xin; Gutiérrez-Urrutia, I.; Emura, Satoshi; Liu, Tianwei; Hara, Toru; Min, Xiaohua; Ping, Dehai; Tsuchiya, Koichi

doi:10.1080/14686996.2019.1600201

Cited by 48 publications

(9 citation statements)

References 51 publications

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“…In the case of ST3 treatment one can observe the presence of diffraction peaks belonging to α-Ti, β-Ti, α"-Ti and possible α -Ti phases (see Figure 7c). Because of the heating at 1000 • C, above β-transus temperature ≈935 • C, and rapid cooling at ambient temperature the α"-Ti phase is generated from parent β-Ti phase [45,46]. The α"-Ti phase was indexed in the orthorhombic crystalline system, with the lattice parameters close to a = 0.296 nm, b = 0.496 nm and c = 0.468 nm.…”

Section: Microstructure Evolution During Tm Processing Of Ti-6246 Alloymentioning

confidence: 99%

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Alluaibi

Cojocaru

Rusea³

et al. 2020

Metals

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The present study investigates the influence of hot-deformation, above β-transus and different thermal treatments on the microstructural and mechanical behaviour of a commercially available Ti-6246 titanium-based alloy, by SEM (scanning electron microscopy), tensile and microhardness testing techniques. The as-received Ti-6246 alloy was hot-deformed—HR by rolling, at 1000 °C, with a total thickness reduction (total deformation degree) of 65%, in 4 rolling passes. After HR, different thermal (solution—ST and ageing—A) treatments were applied in order to induce changes in the alloy’s microstructure and mechanical behaviour. The applied solution treatments (ST) were performed at temperatures below and above β-transus (α → β transition temperature; approx. 935 °C), to 800 °C, 900 °C and 1000 °C respectively, while ageing treatment at a fixed temperature of 600 °C. The STs duration was fixed at 27 min while A duration at 6 h. Microstructural characteristics of all thermomechanical (TM) processed samples and obtained mechanical properties were analysed and correlated with the TM processing conditions. The microstructure analysis shows that the applied TM processing route influences the morphology of the alloy’s constituent phases. The initial AR microstructure shows typical Widmanstätten/basket-weave-type grains which, after HR, are heavily deformed along the rolling direction. The STs induced the regeneration of α-Ti and β-Ti phases, as thin alternate lamellae/plate-like structures, showing preferred spatial orientation. Also, the STs induced the formation of α′-Ti/α″-Ti martensite phases within parent α-Ti/β-Ti phases. The ageing treatment (A) induces reversion of α′-Ti/α″-Ti martensite phases in parent α-Ti/β-Ti phases. Mechanical behaviour showed that both strength and ductility properties are influenced, also, by applied TM processing route, optimum properties being obtained for a ST temperature of 900 °C followed by ageing (ST2 + A state), when both strength and ductility properties are at their maximum (σUTS = 1279 ± 15 MPa, σ0.2 = 1161 ± 14 MPa, εf = 10.1 ± 1.3%).

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Section: Microstructure Evolution During Tm Processing Of Ti-6246 Alloymentioning

confidence: 99%

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Alluaibi

Cojocaru

Rusea³

et al. 2020

Metals

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“…5(a). Several α" martensite plates can be observed and some of them contain transformation twinning structures [15,16]. Upon 5% tensile straining, new deformation bands were induced in the martensite plates, as indicated by the red arrows in Fig The deformation bands were further characterized by TEM on a FIB lift-out sample prepared in the cross-section perpendicular to the sample surface, Fig.…”

Section: Deformation Mechanism Of α" Martensitementioning

confidence: 99%

“…6. The other twin elements (K 2 , η 1 , and η 2 ) of the {112} α" -type I twinning were calculated with the lattice parameters of α"martensite in the Ti-7.5Mo alloy, i.e., a α" = 0.3002 nm, b α" = 0.5033 nm, and c α" = 0.4680 nm [16]. Then, the crystallographic elements are K 1 = {112}, η 1 = <-6.463, -1, 3.732>, K 2 = {-2.586, -1, 4.379}, and η 2 = <312>.…”

Section: Deformation Mechanism Of α" Martensitementioning

confidence: 99%

Deformation mechanisms and effect of oxygen addition on mechanical properties of Ti-7.5Mo alloy with α” martensite

Gutiérrez-Urrutia

Emura

et al. 2020

MATEC Web Conf.

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Effect of oxygen content as an important interstitial solute on the microstructure and mechanical properties of Ti-7.5Mo alloy was investigated. With increasing the oxygen content, the yielding strength, ultimate tensile strength and Young’s modulus of Ti-7.5Mo-xO (x=0, 0.2, 0.3, 0.4, 0.5) alloys increased, while the elongation showing a decreasing tendency. Solid-solution strengthening by the oxygen atoms has been addressed as the main strengthening mechanism. Ti-7.5Mo-xO (x ≤ 0.3) alloys have been regarded with an excellent combination of high yield strength (~640 MPa) and elongation (~28%), as well as low Young’s modulus (~60 GPa). The deformation microstructure of orthorhombic-α” martensite in Ti-7.5Mo alloy was also investigated by tracking a change in the microstructure of a selected area upon tensile deformation. Deformation twins induced by 5% tensile straining was identified as {112}α”-type I twins, which had not been reported before in α”martensite in β-Ti alloys.

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“…TRIP, transformationtoughening, transformation-induced crack closure and other benefits of stress-induced martensitic transformations are not only important for steels. Titanium alloys [14], cobalt alloys [15,16], high entropy alloys [17,18], and various ceramics [19,20] have been reported to benefit from these mechanisms through fcc→body-centered tetragonal (bct), fcc→hexagonal close-packed (hcp), or monoclinic→tetragonal transformations.…”

Section: Introductionmentioning

confidence: 99%

Design of a V–Ti–Ni alloy with superelastic nano-precipitates

et al. 2020

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Stress-induced martensitic transformations enable metastable alloys to exhibit enhanced strain hardening capacity, leading to improved formability and toughness. As is well-known from transformation-induced plasticity (TRIP) steels, however, the resulting martensite can limit ductility and fatigue life due to its intrinsic brittleness. In this work, we explore an alloy design strategy that utilizes stress-induced martensitic transformations but does not retain the martensite phase. This strategy is based on the introduction of superelastic nano-precipitates, which exhibit reverse transformation after initial stress-induced forward transformation. To this end, utilizing ab-initio simulations and thermodynamic calculations we designed and produced a V45Ti30Ni25 (at%) alloy. In this alloy, TiNi is present as nano-precipitates uniformly distributed within a ductile V-rich base-centered cubic (bcc) β matrix, as well as being present as a larger matrix phase. We characterized the microstructure of the produced alloy using various scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. The bulk mechanical properties of the alloy are demonstrated through tensile tests, and the reversible transformation in each of the TiNi morphologies were confirmed by in-situ TEM micro-pillar compression experiments, in-situ high-energy diffraction synchrotron cyclic tensile tests, indentation experiments, and differential scanning calorimetry experiments. The observed transformation pathways and variables impacting phase stability are critically discussed

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Twinning behavior of orthorhombic-α” martensite in a Ti-7.5Mo alloy

Cited by 48 publications

References 51 publications

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Microstructure and Mechanical Properties Evolution during Solution and Ageing Treatment for a Hot Deformed, above β-transus, Ti-6246 Alloy

Deformation mechanisms and effect of oxygen addition on mechanical properties of Ti-7.5Mo alloy with α” martensite

Design of a V–Ti–Ni alloy with superelastic nano-precipitates

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