The effect of alloying on the ordering processes in near-alpha titanium alloys

Попов, А. А.; Rossina, N. G.; Popova, M. B.

doi:10.1016/j.msea.2012.11.043

Cited by 26 publications

(23 citation statements)

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“…Meanwhile, there is a slight decrease in the elongation (El) and the reduction in area (RA). These results are similar to those found in the literature [23][24][25], where the silicide precipitates are considered to lead to an increase in strength and a slight drop in ductility for near α titanium alloys. Singh et al [22] reported that the kinetics of silicide precipitation in Ti-6Al-1.6Zr-3.3Mo-0.3Si (VT9) alloy was faster than in Ti-6Al-5Zr-0.5Mo-0.25Si (IMI685), which was attributed to the higher content of strong β-stabilizing element Mo in the former alloy.…”

Section: Tensile Propertiessupporting

confidence: 91%

“…Meanwhile, there is a slight decrease in the elongation (El) and the reduction in area (RA). These results are similar to those found in the literature [23][24][25], where the silicide precipitates are considered to lead to an increase in strength and a slight drop in ductility for near α titanium alloys. The differences in the tensile properties of the alloys are largely due to their microstructures.…”

Section: Tensile Propertiessupporting

confidence: 91%

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Effects of Trace Si Addition on the Microstructures and Tensile Properties of Ti-3Al-8V-6Cr-4Mo-4Zr Alloy

Dong

Zhang

et al. 2017

Metals

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Abstract:The microstructural evolution and tensile properties of Ti-3Al-8V-6Cr-4Mo-4Zr titanium alloys with various Si contents were investigated. The results revealed that the addition of trace Si and the presence of Zr induced the formation of (TiZr) 6 Si 3 silicides, in the size range from 100 nm to 300 nm. The fine silicide precipitates refined β grains. The tensile strength increased about 40 MPa due to precipitation strengthening and grain refinement, and the ductility of the two alloys was similar. The tensile fracture mode of the alloys was dimple ductile fracture.

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Section: Tensile Propertiessupporting

confidence: 91%

“…Meanwhile, there is a slight decrease in the elongation (El) and the reduction in area (RA). These results are similar to those found in the literature [23][24][25], where the silicide precipitates are considered to lead to an increase in strength and a slight drop in ductility for near α titanium alloys. The differences in the tensile properties of the alloys are largely due to their microstructures.…”

Section: Tensile Propertiessupporting

confidence: 91%

Effects of Trace Si Addition on the Microstructures and Tensile Properties of Ti-3Al-8V-6Cr-4Mo-4Zr Alloy

Dong

Zhang

et al. 2017

Metals

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“…A certain amount of Si element is added to improve its creep performance at high temperatures [8]. These two factors can easily result in the formation of α 2 (Ti 3 Al) in α phase and precipitation of silicide on the α/β interfaces which are dependent on the content of elements and parameters of heat treatment [9]. Over the past 30 years, numerous studies have been carried out on the heat treatment or terminal exposure of these near α Ti alloys.…”

Section: Introductionmentioning

confidence: 99%

Effects of heat treatments on microstructure and tensile properties of as-extruded TiBw/near-α Ti composites

Wang

Huang

et al. 2015

Materials & Design

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“…The particles of the a 2 -phase block intensely the motion of dislocations and thus promote growth in the creep resistance, but commonly embrittle the alloy. At the same time, it has been shown in [17] that at a relatively low aging temperature an a 2 -phase may form by the mechanism of second-kind phase transformation that yields relatively massive (1 -3 mm) regions with ordered structure. In this case the structure contains antiphase boundaries (Fig.…”

Section: Resultsmentioning

confidence: 99%

Isothermal Diagrams of Precipitation of Silicide and Aluminide Phases in Refractory Titanium Alloys

Попов

Popova

2017

Met Sci Heat Treat

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Processes of precipitation of silicides and aluminides in commercial titanium alloys under different modes of heat treatment are studied. The effect of alloying on the types of precipitating particles is considered. The temperature ranges of formation of intermetallics are determined and the possible mechanisms of transformation of particles of different types are discussed. A schematic isothermal diagram of decomposition of metastable phases in refractory titanium alloys is suggested. INTRODUCTIONAs a rule, isothermal and thermokinetic diagrams of decomposition are plotted for a metastable high-temperature phase, the products of decomposition of which contain a low-temperature modification of the material of the matrix [1 -3]. For example, the eutectoid decomposition of austenite in steels is accompanied by formation of ferrite by different mechanisms in combinations with iron carbide. The rate of formation of the carbide phase is comparable to the rate of formation of ferrite. For titanium alloys the eutectoid transformation commonly develops rather slowly, and decomposition of the metastable b-phase develops by the scheme b met ® a + b enr [4]. However, in refractory titanium alloys this may be not the end of the transformation, and silicide phases may form depending on the composition of the alloy and the temperature. In addition, particles of Ti 3 Al titanium aluminide (an a 2 -phase) may precipitate in the alloyed a-phase.The aim of the present work was to analyze the kinetics of precipitation of silicides and aluminides and to plot a diagram of isothermal transformation yielding them in refractory titanium alloys. RESULTS AND DISCUSSIONLet us consider successively the process of precipitation of silicides and aluminides in commercial titanium alloys.Refractory titanium alloys contain a low amount of b-stabilizers, and therefore the incubation period of the b ® a transformation under isothermal conditions does not exceed several tens of seconds [3]. At the same time, the incubation period of formation of silicides usually exceeds several minutes. For example, it has been shown for alloy VT25u [5] that silicides start to precipitate only after an isothermal hold exceeding 8 min at 750°C. At other temperatures the incubation period of the precipitation is longer. Thus, silicides start to precipitate when the alloy acquires b/a phase boundaries. Such boundaries are commonly coherent and flat. In fact, this predetermines the places of future nucleation of silicide particles. Since the solubility of silicon in the b-phase is higher than in the a-phase, such particles chiefly appear in the b-phase on the b/a phase boundaries. The precipitating particles have a structural formula M 5 Si 3 , where the metal is titanium and, if available, zirconium. It has been shown in [6 -10] that silicides of type (Ti, Zr) 5 Si 3 commonly precipitate in alloys of the Ti -Zr -Si system and are denoted S 1 . Particles of these silicides are mostly observed on b/a phase boundaries in the b-phase; at short holds they have a faceted...

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The effect of alloying on the ordering processes in near-alpha titanium alloys

Cited by 26 publications

References 1 publication

Effects of Trace Si Addition on the Microstructures and Tensile Properties of Ti-3Al-8V-6Cr-4Mo-4Zr Alloy

Effects of Trace Si Addition on the Microstructures and Tensile Properties of Ti-3Al-8V-6Cr-4Mo-4Zr Alloy

Effects of heat treatments on microstructure and tensile properties of as-extruded TiBw/near-α Ti composites

Isothermal Diagrams of Precipitation of Silicide and Aluminide Phases in Refractory Titanium Alloys

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