Mechanical Properties Of Ti Research Articles

Microstructure Evolution and Mechanical Properties of Ti and Zr Micro-Alloyed Al-Cu Alloy Fabricated by Wire + Arc Additive Manufacturing

Microstructure Evolution and Mechanical Properties of Ti and Zr Micro-Alloyed Al-Cu Alloy Fabricated by Wire + Arc Additive Manufacturing

Effect of Mo2C addition on the formation of core-rim structure and mechanical properties of Ti(C,N)-WC-Mo2C-(Ni, Co) cermet

Ti(C,N)-based cermets with various Mo2C contents (4, 6, 8, 10, 12 and 14 wt%) were fabricated via vacuum hot-pressing sintering. The results showed that the cermets were comprised of coarse hard phase with a core-rim structure and partial fine rimless hard phase, embedded in Ni/Co binder matrix. Mo2C inhibits the rim growth on the coarse hard phase and hinders the dissolution of the fine rimless hard phase, which improves the mechanical properties of cermets. In addition, with the increasing Mo2C content, a bimodal pattern of X-ray diffraction peaks of (Ti,W,Mo) (C,N) solid solution can be observed, which indicates that high content of Mo2C has a different effect on the W and Mo contents in the white core-grey rim and black core-grey rim hard phase. When the Mo2C addition reaches 12 wt%, the cermet exhibits better wear resistance, which is attributed to a film composed of Ti and Mo oxides formed on the sliding interface. This work provides fundamental knowledge about the formation of core-rim structure and mechanical properties of Ti(C,N)-based cermets with various Mo2C contents.

Effect of Substrate Bed Temperature on Solute Segregation and Mechanical Properties in Ti–6Al–4V Produced by Laser Powder Bed Fusion

Titanium alloys are particularly sensitive to temperature during additive manufacturing processes, due to their dual phase microstructure and sensitivity to oxygen uptake. In this paper, laser powder bed fusion (LPBF) was used in conjunction with a heated substrate bed at 100 °C, 570 °C and 770 °C to produce specimens of Ti–6Al–4V, to investigate the change in mechanical properties and segregation of alloying elements. An initial increase in ductility was observed when increasing the temperature from 100 °C to 570 °C, followed by a significant loss in ductility when samples were produced at 770 °C. A suite of multi-scale characterisation techniques revealed that the as-printed microstructure was drastically different across the range of temperatures. At 100 °C, α + α′ phases were identified. Deformation twinning was extensively observed in the a phase, with Al and V segregating at the twin interfaces. At 570 °C (the most ductile sample), α′, α and nano-particles of β were observed, with networks of entangled dislocations showing V segregation. At 770 °C, no martensitic α′ was identified. The microstructure was an α + β microstructure and an increased volume fraction of tangled dislocations with localised V segregation. Thermodynamic modelling based on the Gibbs-free energy of formation showed that the increased V concentration at dislocations was insufficient to locally nucleate β phase. However, b-phase nucleation at grain boundaries (not dislocations) caused pinning of grain boundaries, impeding slip and leading to a reduction in ductility. It is likely that the increased O-content within specimens printed at increased temperatures also played a key role in high-temperature embrittlement. Building operations are therefore best performed below sub-transus temperatures, to encourage the growth of strengthening phases via solute segregation, and the build atmosphere must be tightly controlled to reduce oxygen uptake within the samples.

Effect of Microstructures on Mechanical Properties of Ti–6.5Al–2Sn–4Zr–4Mo–1W–0.2Si Alloy

The tensile properties at both room temperature and 550 °C are investigated in Ti–6.5Al–2Sn–4Zr–4Mo–1W–0.2Si with three typical microstructures, which are lamellar, bimodal, and equiaxed microstructures. The results show that the yield and ultimate tensile strengths decrease while the ductility increases as the volume fraction of primary α phase increases at both temperatures. The above phenomena result from the decrease in the β transformed microstructure, which consists of fine α and β lamellae with high‐density α/β interfaces blocking dislocation slipping. The yield and ultimate tensile strengths at 550 °C are lower than that at room temperature, and the ductility at 550 °C is higher than that at room temperature, both of which are attributed to the activity of multislipping systems at high temperature.

Omega Phase Formation and Mechanical Properties of Ti–1.5 wt.% Mo and Ti–15 wt.% Mo Alloys after High-Pressure Torsion

The paper analyzes the effect of severe plastic deformation by the high-pressure torsion (HPT) on phase transformations, in particular, on the formation of the ω-phase, and on mechanical properties, such as hardness and Young’s modulus, in Ti alloys with 1.5 and 15 wt.% Mo. Both alloys were pre-annealed at 1000 °C for 24 h and quenched. The microstructure of the initial Ti–1.5 wt.% Mo alloy consisted of the α-phase and α’-martensite, and the initial Ti–15 wt.% Mo alloy contained polycrystalline β solid solution. The hardness tests of the samples were carried out under the load of 10 and 200 mN. The annealed alloys were subjected to HPT, and the micro- and nanohardness of both deformed samples increased up to ~1 GPa compared to their initial state. It turned out that the values of hardness (H) and Young’s modulus (E) depend on the applied load on the indenter: the higher the applied load, the lower H and higher E. It was also found that the HPT leads to the 30% increase in E for an alloy with 1.5 wt.% Mo and to the 9% decrease in E for the alloy with 15 wt.% Mo. Such a difference in the behavior of the Young’s modulus is associated with phase transformations caused by the HPT.

Effect of Mo2c Addition on the Formation of Core-Rim Structure and Mechanical Properties of Ti(C,N)-Wc-Mo2c-(Ni, Co) Cermet

Effect of Mo2c Addition on the Formation of Core-Rim Structure and Mechanical Properties of Ti(C,N)-Wc-Mo2c-(Ni, Co) Cermet

Influence of sintering parameters on the grain growth and mechanical properties of Ti(C,N)-based cermets prepared via mechanical activation and in-situ carbothermal reduction

Series of new type (Ti,Mo)(C,N)-based cermets sintered at different final sintering temperatures were prepared by the mechanical activation and in-situ carbothermal reduction method in vacuum. The grain growth behavior of the complete solid solution cermets was firstly studied by prolonging the holding time at 1400 °C by using XRD, SEM, and TEM. Results indicated that the thermodynamic three-dimensional equilibrium morphology of the hard-phase particles were {111}-faceted and round-edged octahedron, whose growth mechanism were predominated by the two-dimensional nucleation that controlled by the diffusion of the dissolved alloying elements in the binder along the close-packed direction. The microstructure and mechanical properties of the cermets were also studied. The results indicated that either too low or too high sintering temperature could deteriorate the homogeneity and porosity of the cermets. Only when the sintering temperature was 1400 °C, the optimum TRS, hardness, and fracture toughness of the cermets were 2134±30 MPa, 88.0±0.3 HRA, and 20.1±0.3 MPa·m 1/2 , respectively.

Microstructure and mechanical behavior of Ti—Cu alloys produced by semisolid processing

The mechanical properties of Ti—Cu alloys processed via thixoforming were evaluated. Ti—Cu (25, 27, and 29 wt.% Cu) ingots were produced via arc melting, homogenization at 950 °C for 24 h, and hot-forging at 900 °C, followed by thixoforming at a speed of 8 mm/s after isothermal heat treatment at 1035 °C for 300 s. The thixoformed alloys exhibited good mechanical strength, limited plasticity under tensile loading, and reasonable plasticity under compressive loading. The mechanical strength and plasticity decreased as the Cu content increased as a result of the increasing volume fraction of the peritectic Ti2Cu phase (transformed liquid), which exhibited a lower strength and plasticity than the α + Ti2Cu regions (transformed solid). These findings indicated that the trade-off between the mechanical properties and semisolid processability is largely governed by the Cu content.

Investigation on the interfacial microstructure and mechanical properties of Ti alloy/HSLA steel clad plates fabricated by vacuum roll-cladding

The titanium (Ti) alloy/high-strength low-alloy (HSLA) steel clad plate was successfully fabricated by vacuum roll-cladding (VRC), and the effect of heating temperatures on the interfacial microstructure and mechanical properties was studied. The type and distribution of the interfacial intermetallic compounds (IMCs) were the main factors affecting the mechanical properties of the clad plate. Results showed that the TiC particles and clusters formed the nonuniform interface when heated at 850 °C, which tended to cause stress concentration during the shear deformation and resulted in lower bonding strength. A large number of TiC particles and tiny FeTi grains were formed at 900 °C, leading to the best shear strength (320 ± 25 MPa). However, the FeTi was formed adjacent to β-Ti, and the TiFe2 was formed near the steel matrix at 950 and 1000 °C. Subsequently, the nanoscale TiC particles precipitated and distributed discontinuously between FeTi and TiFe2 grains during the colling stage. The sizes of FeTi and TiFe2 grains became coarse at 1000 °C than that of 950 °C, which seriously reduced the shear strength of the clad plate. In the experimental condition, the reaction mechanism for the generation of compounds is that the TiC generation reaction dominated at lower heating temperatures, while the TiFe2 and FeTi generation reaction dominated at higher heating temperatures.

Characterization of ion-induced microstructural changes in oxygen irradiated Ti–6Al–4V

The change in microstructure and mechanical properties ofTi–6Al–4V alloy due to 160 MeV O6+ ion irradiation has been reported here. Detailed X-ray diffraction line profile analyses have been used to evaluate the microstructural parameters and characterize the nature of defects and their arrangements. The results indicate saturation of size of the coherent region, the dislocation density and its arrangement with dose, which points to an optimized final microstructure of irradiated material. This was also supported by the Vicker’s microhardness measurements. Electron back scattered diffraction study was used to assess the changes in microstructure in terms of the evolution of misorientation boundaries within the grains due to irradiation-induced defects. All the results support the radiation resistance nature of Ti–6Al–4V alloy. Finally, comparison has been made with earlier proton irradiation results, and the difference has been related to the nature of the displacement cascade produced by light and heavy ions.

Microstructure and mechanical properties of Ti–Mg lightweight heterostructured materials

To attain an unusual combination of low density and high specific strength in lightweight materials, Ti–Mg heterostructured (HS) materials comprising soft Mg domains embedded in hard Ti domain matrix were developed. Unlike hitherto reported HS materials, Ti–Mg HS materials are characterized by: (i) significant difference in coefficient of thermal expansion (CET) between soft Mg and hard Ti domains, and (ii) soft Mg domains having lower ductility. The influences of the two features on strength and ductility of HS materials remain poorly understood. To address these questions, this paper reports studies on microstructure and mechanical properties of the Ti–Mg HS materials. The Ti–Mg HS materials were prepared by spark plasma sintering of the mixture of Ti and Mg elemental powders. Ti–12Mg achieves tensile yield strength higher than that calculated using the rule-of-mixture and uniform elongation higher than that of cast Mg. Ti–15Mg obtains tensile yield strength higher than that calculated using the rule-of-mixture but uniform elongation lower than that of cast Mg. Each of Ti–20Mg and Ti–29Mg exhibits tensile yield strength lower than that calculated using the rule-of-mixture and uniform elongation lower than that of cast Mg. The mechanisms underlying strength and ductility of these Ti–Mg HS materials were revealed by analyzing the combined effects of heterogeneous deformation induced strengthening and work-hardening with stress concentration originating from the presence of cracks at Ti/Mg domain boundaries as a result of notable difference in CET between Ti and Mg.

Reaction, densification and mechanical properties of Ti 2 AlC x ceramics at low applied pressure and temperature

Ti2AlCx ceramic was produced by reactive hot pressing (RHP) of Ti:Al:C powder mixtures with the molar ratio of 2:1:1-0.5 at 10–20 MPa, 1200–1300°C for 60 min. XRD analysis confirmed the Ti2AlC with TiC, Ti3Al as minor phases in samples produced at 10–20 MPa, 1200°C. The samples RHP at 10 MPa, 1300°C exhibited ≥95 vol.% Ti2AlC with TiC as a minor phase. The density of samples increased from 3.69 - 4.04g/cm3 at 10 MPa, 1200°C, whereas an increase of pressure to 20 MPa resulted from 3.84 - 4.07g/cm3 (2:1:1 to 2:1:0.5). The samples made at 10 MPa, 1300°C, exhibited a density from 3.95 - 4.07g/cm3. Reaction and densification were studied for 2Ti-Al-0.67C composition at 10 MPa, 700–1300°C for 5 min showed the formation of Ti-Al intermetallic and TiC phases up to 900°C with Ti, Al, and carbon. The appearance of the Ti2AlC phase was ≥1000°C; further, as the temperature increased, Ti2AlC peak intensity was raised, and other phases intensities were reduced. The sample made at 700°C showed a density of 2.87g/cm3, while at 1300°C exhibited 3.98g/cm3; further, soaking for 60 min resulted in a density of 4.07g/cm3. Microhardness and flexural strength of Ti2AlC0.8 sample were 5.81±0.21 GPa and 445±35 MPa. This article is protected by copyright. All rights reserved

Synergistic Effect of Sic Particles and Whiskers on the Microstructures and Mechanical Properties of Ti(C,N)-Based Cermets.

The microstructure and mechanical properties of Ti(C,N)-based cermets with the addition of the SiC particles (SiCp) and SiC whiskers (SiCw), were systematically studied in this work. Firstly, the effect of SiCp on the cermets was investigated independently to determine the considerable total amounts of additives, and the results showed that 2.0 wt.% SiCp would lead to optimal properties of the cermet. Then, the influence of SiCp and SiCw additions with the variable ratio on the cermets was studied. The results indicated that when 1.5 wt.% SiCp and 0.5 wt.% SiCw were added; the cermets appeared with the best comprehensive properties, and the transverse rupture strength, hardness, and the fracture toughness of the cermets reached 2520.8 MPa, 88.0 HRA, and 16.56 MPa·m1/2, respectively. This was due to the synergistic strengthening and toughening effect afforded by the reasonable SiCp and SiCw addition, from which the smallest grain size, as well as the most uniform, and completed core-rim structure of the cermets, were achieved.

Influence of multiple laser shock peening treatments on the microstructure and mechanical properties of Ti−6Al−4V alloy fabricated by electron beam melting

Influence of multiple laser shock peening treatments on the microstructure and mechanical properties of Ti−6Al−4V alloy fabricated by electron beam melting

The evolution of microstructure, martensitic transformation and mechanical properties in Ti–V–Al-based shape memory alloys with changing annealing temperatures

In the present study, the effects of annealing temperature on the microstructure, martensitic transformation and mechanical properties of Ti–V–Al-Gd shape memory alloys were investigated. The results revealed that the phase constituents were dependent on annealing temperatures. The coexistence of the α'´ martensite phase, β phase, hard α second phase and ω phase was found in Ti–V–Al-Gd shape memory alloy annealed at 650 °C. With increasing annealing temperature, the amount of β phase and α second phase gradually decreased. Meanwhile, the grain size of the Ti–V–Al-Gd shape memory alloy increased continuously with increasing annealing temperature. Merely α'´→β reverse martensitic transformation was found in all annealed Ti–V–Al-Gd shape memory alloys, regardless of the annealing temperature. The evolution of the martensitic transformation temperatures can be attributed to the compressive effect of the chemical composition, grain size and type and number of second phases. In addition, the yield strength gradually decreased owing to the coarsening of the grain size and reduction in the amount of the α phase, whereas the elongation became superior in Ti–V–Al-Gd shape memory alloy annealed at higher annealing temperatures due to the elimination of dislocations and defects. In proportion, the strain recovery characteristics gradually decreased as the annealing temperature increased from 700 °C to 800 °C.

Модифицирование структурно-фазового состояния и механических свойств пленок Ti – C60 – Ti, имплантированных ионами бора

Changes in the structure, phase composition, and mechanical properties of Ti – C60 – Ti films implanted with B+ ions (E = 80 keV, D = 1 1016 ion/cm2) after annealing in vacuum at temperature 570 K (3 hours) were studied by the methods of atomic force microscopy, X-ray diffraction and nanoindentation. The films were obtained by resistive evaporation in vacuum. Layers of titanium and C60 fullerite were sequentially deposited onto a substrate of oxidized single-crystal silicon. It has been established that during the condensation of the fullerite layer (h = 250 nm) on the underlying titanium layer (h = 120 nm), and then the titanium layer (h = 150 nm) on the fullerite layer, intense diffusion of titanium into the fullerite layer occurs. Implantation of titanium-fullerite-titanium films with boron ions leads to mixing of titanium and fullerite layers, while the size of structural elements increases in comparison with non-implanted films from 40 nm to 80 nm. Auger electron spectroscopy revealed that ion implantation results in an increase in the atomic fraction of oxygen in the films and the formation of a new TixOyC60 phase, which leads to an increase in the nanohardness of the mixed layers. The implanted Ti – C60 – Ti films were annealed in vacuum at T= 570 K for t = 3 h. Thermal annealing results in recrystallization of the fullerite phase and intensive growth of a new TixOyC60 phase with improved mechanical properties.

Microstructure Evolution and Mechanical Properties of Ti and Zr Micro-Alloyed Al-Cu Alloy Fabricated by Wire + Arc Additive Manufacturing

Microstructure Evolution and Mechanical Properties of Ti and Zr Micro-Alloyed Al-Cu Alloy Fabricated by Wire + Arc Additive Manufacturing

Influence of Different Extrusion Methods on the Microstructure, Texture Evolution and Mechanical Property of Ti P /Az31 Composite

Influence of Different Extrusion Methods on the Microstructure, Texture Evolution and Mechanical Property of Ti P /Az31 Composite

Preliminary tribo-electrochemical and biological responses of the Ti-TiB-TiCx in-situ composites intended for load-bearing biomedical implants

Poor tribocorrosion resistance of Ti and its alloys remains as a concern for load-bearing biomedical implants. Despite being an effective method to improve tribocorrosion resistance, titanium matrix composites (TMCs) have yet to be used in this type of applications. In-situ TiB (titanium boride) and TiC (titanium carbide) reinforcement phases have been considered as one of the best options to produce TMCs once these phases present high compatibility and strong interfacial bonding with Ti. Although the effect of these phases on the mechanical properties of Ti has been thoroughly researched in the last years, their effect on corrosion, tribocorrosion and biocompatibility of Ti is yet to be fully understood. In this work, in-situ Ti-TiB-TiCx composites obtained by reactive hot pressing showed identical corrosion response compared to the unreinforced Ti but displayed improved tribocorrosion behaviour. Under 0.5 N load, composites presented as average a reduction of 51% in wear volume loss and under 10 N the reduction was up to 93%. Early biological tests showed promising results, as composites were biocompatible and induced osteoblasts spreading and possibly proliferation most probably due to composite chemistry and surface hardness.

Comparison of microstructure, crystallographic texture, and mechanical properties in Ti–15Mo–5Zr–3Al alloys fabricated via electron and laser beam powder bed fusion technologies

Depending on the application, establishing a strategy for selecting the type of powder bed fusion technology—from electron beam (EB-PBF) or laser powder bed fusion (L-PBF)—is important. In this study, we focused on the β-type Ti–15Mo–5Zr–3Al alloy (expected for hard-tissue implant applications) as a model material, and we examined the variations in the microstructure, crystallographic texture, and resultant mechanical properties of specimens fabricated by L-PBF and EB-PBF. Because the melting mode transforms from the conduction mode to the keyhole mode with an increase in the energy density in L-PBF, the relative density of the L-PBF-built specimen decreases at higher energy densities, unlike that of the EB-PBF-built specimen. Although both EB-PBF and L-PBF can obtain cubic crystallographic textures via bidirectional scanning with a 90° rotation in each layer, the formation mechanisms of the textures were found to be different. The <100> texture in the build direction is mainly derived from the vertically grown columnar cells in EB-PBF, whereas it is derived from the vertically and horizontally grown columnar cells in L-PBF. Consequently, different textures were developed via bidirectional scanning without rotation in each layer: the <110> and <100> aligned textures along the build direction in L-PBF and EB-PBF, respectively. The L-PBF-built specimen exhibited considerably better ductility, but slightly lower strength than the EB-PBF-built specimen, under the conditions of the same crystallographic texture and relative density. We attributed this to the variation in the microstructures of the specimens; the formation of the α-phase was completely absent in the L-PBF-built specimen. The results demonstrate the importance of properly selecting the two technologies according to the material and its application.