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•Cu addition to the Ti-5553 alloy resulted in the precipitation of nanometric Ti2Cu.•Upon aging heat treatment, α phase precipitation was affected by the presence of Cu.•Cu addition ...to the Ti-5553 alloy enhanced α phase precipitation.•Cu addition to the Ti-5553 alloy improved strength at the expense of ductility.
Metastable β Ti alloys in the β quenched condition exhibit relatively low mechanical strength. Aging heat treatment can improve mechanical strength because of controlled α phase precipitation into the β matrix. This study aimed to examine the aging response of a β quenched Cu-modified Ti-5553 alloy, α phase precipitation therein, and the resulting mechanical behavior. It was found that Cu addition resulted in the precipitation of a nanometric Ti2Cu intermetallic compound, which upon aging, affected α phase precipitation and therefore increased the ultimate tensile strength from 1147 to 1222 MPa at the expense of ductility.
In this paper, using electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) characterization, we systematically investigated the dynamic recrystallization (DRX) mechanism ...and its effects on the texture orientation and grain refinement of Ti6Al4V titanium alloy subjected to laser shock peening (LSP). The results indicated shear bands-induced DRX mechanism played a vital role in texture transition and grain refinement during LSP. Based on the observation, the DRX mechanism was determined as continuous dynamic recrystallization (CDRX). Due to the wide range of local misorientation of grains within shear bands, the new dynamic recrystallized grains exhibited preferred selection of 1−21−0 orientation, thereby resulting in the original 011−0 fiber component weakening. The deformation is mainly supported by basal slip and pyramidal <c+a> slip in α phase during LSP, activating massive non-basal dislocation for the subsequent CDRX process. The more nucleation sites available closer to the surface, as well as the increasing adiabatic temperature induced by ultra-high strain rate deformation there, contributed to the improved DRX, resulting in more intense grain refinement on the top surface.
•Continuous dynamic recrystallization occurred during laser shock peening.•The new dynamic recrystallized grains with a wider crystal crystallographic orientation nucleate from shear bands.•The dynamic recrystallization process was mainly supported by basal slip and pyramidal <c+a> slip.•The finer grains are formed on the surface by dynamic recrystallization.
To improve the yield of titanium alloy, a certain amount of TiOsub.2 can be added to the refining slag system of Ti-bearing steel grades. With the aim of understanding the effect of TiOsub.2 addition ...on the melting behaviors of CaO-SiOsub.2-30%Alsub.2Osub.3-5%MgO refining slags, the melting points of the slags and the phases in the slags are herein studied at different temperatures in the laboratory. It is found that with the increase in TiOsub.2 content (0~10%) in slag, the melting point of the slags drops first, and then rises. The effect of slag basicity (R = w(CaO)/w(SiOsub.2), 2~10) shows a similar tendency. The TiOsub.2 content and slag basicity evidently affect the precipitated phases in the slags at a lower temperature (e.g., 1310 °C). With the increase in basicity, the liquid areal fraction increases first, and then decreases. Moreover, the CaO-TiOx-Alsub.2Osub.3 phase (CTA) and its TiOx content show a declining trend at 1310 °C. When R = 10, large amounts of solid calcium aluminates are precipitated. With TiOsub.2 addition in the slags, the TiOx contents in both liquid and CTA phases increase. Excessive TiOsub.2 addition (e.g., 10%) leads to the large precipitation of CTA, as well. To improve the melting properties of the slag and the yield of Ti alloys during the refinement of Ti-bearing steel grades, a small TiOsub.2 addition (e.g., 5%) may be considered.
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The performance of many metal biomedical implants – such as fusion cages for spines – is inherently limited by the mismatch of mechanical properties between the metal and the ...biological bone tissue it promotes. Here, an alloy design approach is used to isolate titanium alloy compositions for biocompatibility which exhibit a modulus of elasticity lower than the Ti-6Al-4V grade commonly employed for this application. Due to the interest in alloys for personalised medicine, additive manufacturability is also considered: compositions with low cracking susceptibility and with propensity for non-planar growth are identified. An optimal alloy composition is selected for selective laser melting, and its processability and mechanical properties tested. Additive manufacturing is used to engineer an heterogeneous microstructure with outstanding combined strength and ductility. Our results confirm the suitability of novel titanium alloys for lowering the stiffness towards that needed whilst being additively manufacturable and strong.
Titanium is the most used material for implant production. To increase its biocompatibility, continuous research on new coatings has been performed by the scientific community. The aim of the present ...paper is to prepare new coatings on the surfaces of the pure Ti Grade 2 and the Ti6Al4V alloy. Three types of coatings were achieved by applying anodization and chemical vapor deposition (CVD) methods: TiOsub.2 nanotubes (TNTs) were formed by anodization, carbon nanotubes (CNTs) were obtained through a metal-catalyst-free CVD process, and a bilayer coating (TiOsub.2 nanotubes/carbon nanostructures) was prepared via successive anodization and CVD processes. The morphology and structure of the newly developed coatings were characterized using SEM, EDX, AFM, XRD, and Raman spectroscopy. It was found that after anodization, the morphology of the TiOsub.2 layer on pure Ti consisted of a “sponge-like” structure, nanotubes, and nano-rods, while the TNTs layer on the Ti alloy comprised mainly nanotubes. The bilayer coatings on both materials demonstrated different morphologies: the pure Ti metal was covered by a layer of nanotubular and nano-rod TiOsub.2 structures, followed by a dense carbon layer decorated with carbon nanoflakes, and on the Ti alloy, first, a TNTs layer was formed, and then carbon nano-rods were deposited using the CVD method.
In this paper, Co-based composite coatings were fabricated by laser cladding Co42 + B4C mixed powders on Ti-6Al-4V titanium alloy. The comprehensive effects of laser power and scanning velocity on ...the microstructure evolution and wear property of the laser cladding coatings were studied. Results indicated that the coatings were mainly comprised of γ-Co/Ni, TiC, TiB2, TiB, NiTi, CoTi, CoTi2, and Cr7C3. With the decreasing of laser specific energy (from 12.7 kJ cm−2 to 4.9 kJ cm−2), the TiC dendrites and TiB particles were refined. Compared with the Ti-6Al-4V titanium alloy, the microhardness and wear resistance of the composite coatings were enhanced obviously. Lower laser specific energy led to higher microhardness and better wear resistance owing to more TiB2 bulks distributed in the cladding coating.
•Composite coatings reinforced with multiple phases were fabricated.•The microstructure was refined with the decreasing of laser specific energy.•Lower laser specific energy led to higher microhardness and better wear resistance.
The prior β grain structure is recognized to be an important factor governing the mechanical properties of laser additive manufacturing (LAM) titanium alloys (ti-alloys) components. Five kinds of ...ti-alloys plates were fabricated by LAM process aiming to investigate the solidification behavior and grain morphology. Full columnar grains, full equiaxed grains and a special mixed grains structure were observed in LAM TC4, TB6 and TC11 plates, respectively, indicating that the formation tendency and volume fraction of equiaxed grains in LAM ti-alloys plates increase gradually with the increasing alloying content. It was proposed the formation of equiaxed grains is a multifactor functioning result of the constitutional supercooling and the remaining powders in the local melting pool.
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•Grain morphologies of five LAM ti-alloys are examined.•LAM TC4 and TB6 present full columnar and equiaxed grains respectively.•With the increasing Q of ti-alloys, the fraction of columnar grains decreases.•The equiaxed grains is a combined result of CS and remaining powders.
Owing to superior physio-chemical characteristics, titanium alloys are widely adopted in numerous fields such as medical, aerospace, and military applications. However, titanium alloys have poor ...machinability due to its low thermal conductivity which results in high temperature during machining. Numerous lubrication and cooling techniques have already been employed to reduce the harmful environmental footprints and temperature elevation and to improve the machining of titanium alloys. In this current work, an attempt has been made to evaluate the effectiveness of two cooling and lubrication techniques namely cryogenic cooling and hybrid nanoadditive–based minimum quantity lubrication (MQL). The key objective of this experimental research is to compare the influence of cryogenic CO
2
and hybrid nanofluid–based MQL techniques for turning Ti–6Al–4V. The used hybrid nanofluid is alumina (Al
2
O
3
) with multi-walled carbon nanotubes (MWCNTs) dispersed in vegetable oil. Taguchi-based L9 orthogonal-array was used for the design of the experiment. The design variables were cutting speed, feed rate, and cooling technique. Results showed that the hybrid nanoadditives reduced the average surface roughness by 8.72%, cutting force by 11.8%, and increased the tool life by 23% in comparison with the cryogenic cooling. Nevertheless, the cryogenic technique showed a reduction of 11.2% in cutting temperature compared to the MQL-hybrid nanofluids at low and high levels of cutting speed and feed rate. In this regard, a milestone has been achieved by implementing two different sustainable cooling/lubrication techniques.
![Effect of TiO[sub.2] Additi...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2075-4701/small "Effect of TiO[sub.2] Addition on the Melting Behaviors of CaO-SiO[sub.2]-30%Al[sub.2]O[sub.3]-5%MgO System Refining Slags")
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