Addition Of Ti Research Articles

Influence of Various Alloying Element Additions on Microstructure and Magnetic and Mechanical Properties and Corrosion Behavior of Cast Fe–Ga–Z Shape Memory Alloys

Fe–Ga alloys are attractive materials where high mechanical strength, toughness, ductility, and large low-field magnetostriction combine to give unique properties. Adding alloying elements is an effective method to further enhance these properties. In order to integrate these alloys into the operating environments, e.g., micro-robots and magnetic actuators, the corrosion behavior should be addressed. This work analyzed the microstructure, magnetization, hardness, and corrosion properties of Fe81Ga19−xZx (X = 5 at.% of Ni, Mn, or Ti, and 2 at.% Al; separately) alloys. X-ray diffraction (XRD), scanning electron microscope-electron (SEM), vibrating sample magnetometer (VSM), Vickers hardness (HV), and a potentiostat were used for characterization. XRD revealed that the prominent peak belongs to the bcc disorder A2 phase and a small peak for the cubic order L12 phase. Fe–Ga–Al alloy got the maximum Ms value, while Fe–Ga–Mn alloy gained the lowest one. However, the Mr and Hc properties for Fe–Ga alloy were distinctly improved by adding Al but slightly affected by doping Mn. Addition of Ti achieved the highest hardness, followed by Ni, Mn, and Al. The microstructure of the different alloys significantly influenced their corrosion behavior. Fe–Ga–Mn alloy with the fine globular grain structure showed the lowest corrosion rate (C R = 0.03 mm/year), whereas Fe–Ga–Al alloy with the coarse longitudinal grains exhibited the highest corrosion rate (C R = 0.19 mm/year).

Tailoring microstructure and tensile properties of low-cost AlCrFeNi-based high-entropy alloys via Co and/or Ti addition

Al-Cr-Fe-Ni high-entropy alloys (HEAs) have low cost but suffer from intrinsic brittleness, leading existing research to concentrate on compressive properties. This study explores alloying strategies to improve tensile properties for these HEAs. Minor elements including 5 at.% Co, 5 at.% Co + 3 at.% Ti, and 5 at.% Co + 5 at.% Ti are added to investigate their impact on microstructure, tensile properties, and solidification behavior for Fe30Ni35Cr21.25Al13.75 HEA. The addition of both Co and Ti has a synergistic effect on the alloys; however, it does not alter the types of phases present, as the face-centered cubic (FCC), body-centered cubic (BCC), and B2 phases are maintained. Specifically, the increase of Ti content promotes the transformation of the primary phase from FCC to BCC and causes the BCC phase to undergo spinodal decomposition. The addition of Co alone decreases the strength, whereas the synergistic combination of Co and Ti enhances the yield strength (from ∼571 MPa to ∼625 MPa) and ultimate tensile strength (from ∼1112 MPa to ∼1288 MPa). Nonetheless, the total elongation is only reduced by 1.5% with this combination. Specially, introducing 5% Ti into the alloy instantly renders it brittle. These results provide valuable insights into improving the mechanical properties and understanding the solidification behavior of low-cost Al-Cr-Fe-Ni HEAs through synergistic alloying.

Microstructure and mechanical properties of cold spray additive manufactured and post heat treated high-entropy alloys with mixed CoCrFeNi and Ti powders

Solid-state cold spray additive manufacturing has the potential to fabricate high-strength bulk high-entropy alloys (HEAs). Through systematic experiments, this study examined the microstructure and mechanical properties of cold spray fabricated bulk HEAs with mixed CoCrFeNi and Ti powders and explored the effects of Ti content in 4 and 7 at% and post-heat treatment at 800 °C/6 h and 1000 °C/6 h. It is found that the bulk HEAs are highly densified and remain nearly defect-free after the post-heat treatment. The addition of Ti serves as an mixing powder effect to further densify the alloys. Moreover, the addition of Ti and post-heat treatment promote the formation of fine precipitates, including Fe2Ti, Co2Ti, CrFe, CoTi2, and Ni3Ti, which contributes to the strengthening of the alloys. Furthermore, post-heat treatment improves the cohesion of the alloys and yields fine and relatively uniform grains by stimulating static recovery and recrystallization. These synergistic effects improve the hardness, elastic modulus, strength, and ductility properties. The average hardness and elastic modulus of the bulk alloys are as high as 377.6 HV and 94.8 GPa, respectively; the best ultimate tensile strength and elongation to failure are 626.7 MPa and 22.1 %, respectively. Synchrotron X-ray diffraction validates the complex precipitates formed and confirms that there is no phase change during tension. The study offers insights into the microstructure and mechanical properties of cold spray additive manufactured HEAs and the effects of mixed powders and post-heat treatment on tuning microstructure and properties.

Wetting and interfacial reactions in liquid Au-Ti alloys / ZrO2 system

This study investigates wetting of zirconia by Au-Ti alloys containing 0.6 to 4 wt% Ti in view of brazing zirconia to titanium with pure gold for biomedical applications. Experiments were carried out using sessile and dispensed drop methods under high vacuum at 1040-1250 °C. Bulk drops and Au-Ti / ZrO2 interfaces were characterized by SEM and FEG-SEM with EDXS analysis. While Au does not wet zirconia, the contact angle θ being ∼ 120°, the addition of Ti in Au leads to a significant improvement of wetting due to the formation of a wettable oxide layer at Au-Ti / ZrO2 interface. The nature of this oxide was determined by X-ray diffraction of the reaction layer after the detachment of the droplet from the substrate or after the dissolution of the droplet. The mechanism of formation and growth of the oxide layer and its growth kinetics were determined based on fine analysis of the Au-Ti / oxide layer / ZrO2 interfacial system.

Achieving High Self-Lubricating Performance of Al-Bi-Sm-Ti Alloys Based on the Intermetallic Compounds

Al-Bi immiscible alloys, as wear resistance material, have attracted increasing attention in the past. The solidification processing of alloys plays a significant role in the final solidification microstructure and properties of immiscible alloys. Here, we present a strategy to produce a homogeneous microstructure in Al-Bi alloys based on intermetallic compounds. With the addition of Sm and Ti, the effect on the microstructure and properties was discussed in detail. The Al-Bi-Sm-Ti alloys achieve high self-lubricating performance, referring to the values of the coefficient of friction and wear rate. The intermetallic compounds formed were regarded as the main anti-friction and anti-wear factors. The results of numerical simulation indicate that microsegregation in Al-Bi alloys was retarded based on the intermetallic compounds. The coefficient of friction of the Al-Bi-1Sm-2Ti alloy was 46.2% lower than that of the Al-Bi alloys at 300 m. This research provides a new perspective and guidance for designing and fabricating composites with superior self-lubricating properties.

Influences of Ti and Mo alloying on the microstructure and properties of laser cladding for CoCrFeNi high-entropy alloys

The CoCrFeNiTi_(1-x) Mo_x high-entropy-alloy coating was prepared using a powder presetting method. The work investigated the influences of Ti and Mo addition on the microstructure and properties of CoCrFeNi high-entropy alloys. The first-principles calculation showed that CoCrFeNiTi_(1-x) Mo_x was mainly composed of the FCC phase, BCC phase, and IMCs. The coating exhibited high hardness, and the mechanical stability of the high-entropy alloys of FCC and BCC phases was maintained when x = 0.5. The coating primarily consisted of FCC, BCC, σand CoTi2 phases when x ≤ 0.75. The coating primarily consisted of FCC, BCC, σand Co2Mo3 phases when x = 1. It exhibited high microhardness, elastic modulus, elastic stiffness, and wear resistance when x = 0.5. Its average microhardness, local elastic modulus, and elastic stiffness were 873.28 HV0.5, 265.5606 GPa, and 102.8008 GPa, respectively. Besides, COF and the wear mass loss were 0.7026 mm3 and 0.0410 mm3, respectively. The coating exhibited exceptional corrosion resistance with a self-corrosion voltage of −0.700 V and a self-corrosion current of 5.387e-007 A when x = 1. The results offer practical guidance for preparing high-entropy-alloy coatings with various advantages as well as a theoretical foundation for preparing such alloys by laser cladding.

Unveiling the effects of Ti microalloying and thermomechanical processing on recrystallization behavior and mechanical properties of type 316 stainless steel

For the titanium-stabilized austenitic stainless steels, the interaction of precipitation due to the addition of Ti and the recrystallization process is an important aspect of grain refinement, which needs more systematic investigations. Accordingly, in the present work, the effects of Ti microalloying and thermomechanical processing on the recrystallization behavior and mechanical properties of type 316 stainless steel were investigated. It was revealed that the strain-induced α′-martensitic transformation in these metastable alloys is sensitive to the presence of Ti and C in solid solution or their presence as TiC carbides in the aged condition, as well as the temperature of rolling and reduction in thickness. During annealing, the reversion of deformation-induced α′-martensite to austenite and primary recrystallization resulted in the formation of fine-grained equiaxed microstructures, where the precipitation of TiC and sigma-phase was found to be important in the retardation of recrystallization and grain growth (by Zener pinning mechanism) as well as refining the grain size. Annealing the cold rolled 316Ti stainless steel at 800 °C led to a fine grain size of ∼2.5 μm with the precipitation of sigma-phase; while annealing at 900 °C resulted in a coarser grain size of 4 μm but without the presence of the unfavorable sigma-phase. The yield stress of 476 MPa, ultimate tensile strength of 805 MPa, and total elongation of 68 % were obtained for the latter, revealing the merits of Ti addition and thermomechanical processing for the improvement of mechanical properties.

Influence of Si, Ti, and Cu as alloying elements on the wettability and reactivity of an Al/B4C system

The wettability and reactivity of Al alloys and B4C are of vital importance in the production of B4C-reinforced Al-matrix composites. However, previous research has primarily focused on pure Al/B4C systems, with little focus on alloying elements. In this paper, we investigated the influence of Si, Ti and Cu as alloying elements on the wettability and interfacial reactivity of an Al/B4C system using improved sessile drop methods. The B4C substrate was not wetted by molten Al at 700−1000 °C, with initial contact angles higher than 100°. However, rapid spreading was observed in the initial stages due to the formation of Al3BC and Al4C3. Si had a noticeable effect on the interfacial wettability only at levels of 15 wt% or above, with the interfacial products changing from Al3BC and AlB2 to SiC-dominated phases. The addition of Ti to Al led to the formation of TiB2-dominated interfacial products, which replaced the Al3BC and AlB2 phases, with the spreading kinetics mainly controlled by interfacial reactions in the early stages and the diffusion of Ti from the bulk of the drop to the triple line in the later stages. The addition of Cu had a negligible effect on the wettability but slightly weakened the formation of AlB2 by promoting substrate dissolution.

Upgrading of plastic waste-derived wax through air gasification using promoted Ni/Al2O3 catalysts for H2 generation

Catalytic air gasification of plastic waste-derived wax (PW) was performed using Ni/X-Al2O3 (X = Ti, Sr, or La) catalysts to produce H2-rich gas for the first time. For this purpose, X-Al2O3 supports were primarily synthesized by doping different promoters into the Al2O3 structure, followed by the loading of Ni. The catalytic performances of prepared catalysts were compared with that of 10Ni/Al, prepared by impregnation of Ni into commercial γ-Al2O3. Compared with using 10Ni/Al, the use of Ni/X-Al2O3 catalysts resulted in higher activity and selectivity, wherein the highest gas yield (74.78 wt%) and H2 selectivity (25.30 vol%) were achieved using 10Ni/5Ti-Al. Also, the coke yield effectively decreased when using Ni/X-Al2O3 catalysts, particularly 10Ni/5Ti-Al, compared with using 10Ni/Al. These findings are ascribed to the versatile effects of well-dispersed metallic Ni active sites, increased density of Lewis acidic sites at the expense of Brønsted acid sites, and enhanced oxygen transfer capacity of the catalyst owing to Ti addition. Moreover, increasing the concentrations of Ni (up to 10 %) and Ti (up to 5 %) enhanced the catalytic activity and selectivity for H2 production. Increasing the temperature (up to 750 °C) showed a positive effect on the production of H2-rich gas. Furthermore, varying the catalyst-to-feedstock ratio affected the gas yield and H2 selectivity.

Influence of micro-segregation on the microstructure, and microhardness of MoNbTaxTi(1-x)W refractory high entropy alloys: Experimental and DFT approach

In recent times, MoNbTaW Refractory High Entropy Alloys (RHEAs) have drawn attention due to their exciting high-temperature applications and efforts are being made to improve their properties further. Alloying addition is an effective and practical approach to enhancing material properties. Ti is well known for its strength, low density, and corrosion resistance and its role in the properties of MoNbTaW-based RHEAs is required to be understood. RHEAs are commonly synthesized by vacuum arc melting (VAR) process and micro-segregation of the elements is reported. However, the effect of micro-segregation on MoNbTaW RHEAs is not well understood. Hence, the present work deals with the addition of Ti and micro-segregation on the structure, microstructure, and indentation behavior of MoNbTaW RHEAs. A novel non-equiatomic MoNbTaxTi1-xW (x = 0, 1, and 0.5) RHEAs were prepared by vacuum arc melting (VAR) process. The structure and microstructure of these RHEAs were ascertained through X-ray diffraction (XRD) and transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with EDS for ascertaining the nominal chemical composition. The as-cast MoNbTaxTi1-xW (x = 0, 1, and 0.5) RHEAs contains two BCC phase having slightly different lattice parameter i.e., BCC1 (a = 0.324 nm) and BCC2 (a = 0.323 nm) close to Ti and W respectively. These as-cast RHEAs having dendritic and inter-dendritic regions were found to be enriched in W and Ta, and Mo, Nb and Ti respectively. The microhardness of these RHEAs was investigated through instrumented indentation techniques. The microhardness of the BCC1 and BCC2 phases was found to be ∼4.5 GPa and 5.7 GPa. Further, the influence of Ti addition on the structure, elastic constant, and microhardness were estimated from the perspective of the first principle approximation. The special quasi-random structure (SQS) was used for first-principle calculations. The strengthening mechanisms influencing the mechanical properties in these BCC RHEAs were discussed in details. The experimental results were in good agreement with the results pertaining to theoretical modelling, demonstrating the effectiveness of these methods in predicting the structure and mechanical properties of RHEAs.

Controlling the addition of solute Ti in Al-Mg-Zn-Cu-Ni alloy for enhanced high-temperature creep properties

This study aims to fundamentally understand the effect of 0.1 at% Ti addition (for introducing solute Ti with low diffusivity into the α-Al matrix) on the microstructure and high-temperature mechanical performance of a heat-resistant Al–5Mg–3.5Zn–2Cu–2Ni (at.%) quinary alloy subjected to heat treatments. The precipitation morphologies of the T-Al6Mg11Zn11 phase are systematically characterized in terms of the distribution of solute Ti, which is controlled by a peritectic reaction during solidification. High-temperature strength and creep properties (200 °C/105 MPa) are examined using the Ti-added alloy specimen and compared with the results of Ti-free quinary alloy specimens. In the Ti-added alloy, solute Ti is distributed within the dendritic α-Al phases formed through the peritectic reaction. The precipitation morphologies vary depending on solute Ti contents in the α-Al matrix after isothermal aging at 200 and 300 °C. Numerous fine T-phase precipitates are homogeneously dispersed in the α-Al matrix containing high solute Ti content. Fine precipitation morphologies appear stable even after long-term exposure at 200 °C. Ti addition extends creep rupture life (at 200 °C) without the loss of static high-temperature strength and room-temperature ductility. The improved creep properties could be responsible for the reduction in creep rate by the refined precipitation morphologies in the α-Al matrix containing higher solute Ti contents. Local coarsening of the precipitates occurs owing to the solute Ti during creep (under stress). The mechanism is discussed in terms of the effect of Ti addition on the phase equilibria between the α-Al and other intermetallic phases.

Study on Friction and Corrosion Performance of CrTiBN Coating in Artificial Seawater Environment

CrN, CrTiN, and CrTiBN coatings were deposited onto 316 stainless steel substrates using multi-arc ion plating techniques. Their morphology, microstructures, friction performance, and corrosion resistance in simulated seawater were systematically characterized. After being analyzed with X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy, the results revealed that CrN coatings had a primary face-centered cubic CrN structure. Following the addition of Ti and B elements, CrTiBN coatings exhibited a cross-sectional structure with hexagonal TiB2 and amorphous BN, displaying the most compact structure. Electrochemical impedance spectroscopy tests indicated that CrTiBN coatings had the highest polarization resistance, the highest phase angle, and the widest frequency range. During electrochemical polarization curve tests, CrTiBN coatings displayed a corrosion potential of 0.11 V, a polarization resistance of 2470 kΩ·cm2, and a minimal corrosion current of 1.94 × 10−8 A/cm2, demonstrating outstanding corrosion resistance. The results from the friction tests indicated that CrTiBN coatings exhibited the lowest friction coefficients of 0.16 and wear rates of 8.18 × 10−7 mm3/Nm. Insights gained from electrochemical friction–corrosion tests revealed that CrTiBN coatings maintained the highest Open Circuit Potential (OCP) throughout the corrosion and friction process. In summary, the introduction of Ti and B has clearly enhanced the friction and corrosion resistance properties of CrTiBN coatings in comparison to CrN coatings.

Study on the wear resistance and mechanism of AlCrCuFe2NiTix high-entropy surfacing alloys

The revolutionary design concept of high-entropy alloys has brought new opportunities and challenges to the development of advanced metal materials. In this work, the design idea of a high-entropy alloy is combined with the characteristics of flux cored wire, and AlCrCuFe2NiTix high-entropy flux cored wires were prepared. AlCrCuFe2NiTix high-entropy surfacing alloys were prepared using gas metal arc welding technology. The wear properties of AlCrCuFe2NiTix high-entropy surfacing alloys were analysed using an MFT-4000 reciprocating friction and wear tester. The phase composition and microstructure of AlCrCuFe2NiTix high-entropy surfacing alloys were analysed using XRD, SEM, EBSD, and TEM, and the strengthening mechanism and wear mechanism of the alloy were discussed. The results show that AlCrCuFe2NiTix high-entropy surfacing alloys are composed of the BCC/B2 + FCC phase. With increasing Ti content, the Laves phase begins to precipitate and exists stably. The microstructure of the alloy presents a typical dendritic structure, and the DR region is rich in Fe, Cr, Al and Ni. The BCC and B2 phases are coherently distributed in the dendrites with a spinodal decomposition network structure. The ID region is rich in Cu and Ti, and the Cu-rich FCC phase is segregated in the form of nanoparticles in the ID region, while the lamellar Laves phase precipitates in the ID region. With increasing Ti content, the microhardness of AlCrCuFe2NiTix high-entropy surfacing alloys shows an increasing trend, while their wear loss, friction coefficient, specific wear rate and other indicators show a trend of first decreasing and then increasing. The maximum microhardness is 597 HV, and the minimum specific wear rate is 9.1606 × 10−8 mm3/N mm. This is mainly because the precipitation of the B2 coherent phase and Laves phase hinders the movement of dislocations, resulting in an improvement in the strength and microhardness of the alloy. However, excessive Ti addition causes the Laves phase to increase sharply and segregate in the ID region, which is extremely prone to stress concentration during dislocation movement, thus inducing crack initiation. The fractured Laves phase exacerbates the grain-abrasion of the alloy and reduces its wear resistance.

Elemental effect on the phase formation and mechanical properties in the FeNiMnCuAlTi alloy system

The FeNiMnCuAlTi alloys were prepared using the arc-melting method by varying the individual elements. The change in microstructure and mechanical properties of the alloys due to the changes in the elemental composition was carried out by X-ray diffraction, Scanning Electron Microscopy, and transmission electron microscopy. Equiatomic composition exhibited the B2_BCC and C_14 Laves phase, whereas increasing the Fe content in the alloys enhanced the formation of the BCC phase. Cu and Ni enhanced the formation of the FCC phase and the addition of Al and Ti favored the formation of intermetallics. Cu tends to segregate in the inter-dendritic region in all these alloys by forming a Cu-Mn-rich FCC phase. Fe, Ni, Cu and Mn-rich alloys showed good plasticity, whereas Al and Ti-rich samples are extremely brittle. A high compressive yield strength of 2016 MPa, 1526 MPa, and 1255 MPa was observed for the high-entropy alloys Fe30(NiMnCuAlTi)70, Ni30(FeMnCuAlTi)70, and Mn30(NiFeCuAlTi)70 respectively, with plasticity varying between 3% to 10%. Whereas medium entropy alloys showed a lower compressive yield strength but with increased plasticity e.g., a compressive yield strength of 1525 MPa and 27% plasticity for the case of Fe50(NiMnCuAlTi)50 was observed. The good combination of strength and plasticity is due to the presence of the FCC/BCC phase with a fine uniform distribution of intermetallic phases.

Photocatalytical and corrosion behavior of sputtered zirconium oxynitride thin films doped with titanium

ZrTiON coatings were deposited by reactive magnetron sputtering process of a single Zr target, while Ti was added by placing Ti ribbons on the erosion track of the Zr sputtering target. The variation of parameters such as the number of Ti ribbons, the applied sputtering current, and the reactive gas flow led to obtaining different sample configurations. The coatings were analyzed in terms of chemistry (chemical composition and chemical states) by X-ray Photoelectron Spectroscopy, morphology by Atomic Force Microscopy, surface energy, photodegradation tests, electrochemical studies, and accelerated corrosion tests. It was found that the coatings show features of oxides, nitrides, and oxynitrides, depending on the deposition conditions applied. The photodegradation efficiency regarding methylene blue solutions under visible light varies between 58% and 96%, depending on the type of illuminant and the sample characteristics, while the lowest corrosion rate was exhibited by the reference samples deposited without the addition of Ti. The samples doped with Ti and deposited with 1.5 A sputtering current exhibited a more efficient photodegradation effect, compared to the reference ZrON sample. The accelerated corrosion tests showed that the coatings deposited with an applied current of 2 A behaved significantly better than the ones deposited with 1.5 A sputtering current after 8 h of exposure to the water vapor and sulfur dioxide gas atmosphere.

Microstructures in the Baima layered intrusion, SW China: Constraints on the late-stage magmatic processes during solidification of a crystal mush

Magmatic microstructures in layered intrusions record key petrographic evidence for the late-stage magmatic processes that took place during solidification of a crystal mush. Systematic examination of the magmatic microstructures can reveal dynamic evolution of interstitial liquid in crystal mush, which however has been only conducted in a few studies on layered intrusions by far. In order to constrain the late-stage magmatic processes related to the Fe-Ti oxide-bearing layered intrusions, we investigated the magmatic microstructures of the Baima intrusion in the Panxi region (SW China). The intrusion is divided into three major units from the base upwards, including the lower zone (LZ), middle zone (MZ) and upper zone (UZ). Through detailed examination of a series of drill core samples, we found several different types of reactive microstructures, such as replacive symplectites, fish-hook pyroxene/olivine/amphibole and amphibole rim. Replacive symplectites include fine-grained, lamellar intergrowths of An-rich plagioclase + olivine/clinopyroxene/amphibole/phlogopite/biotite that are rooted to Fe-Ti oxides and replacing plagioclase primocrysts (Type 1) and intergrowths of An-rich plagioclase + orthopyroxene/olivine/amphibole that are rooted to olivine and replacing plagioclase primocrysts (Type 2). These microstructures are particularly abundant in the LZ except for the Type 2 symplectites, which are rare throughout the intrusion. An-rich plagioclase in the replacive symplectites and fish-hook textures have An contents up to 96, much higher than those of plagioclase primocrysts. Overall, fish-hook amphibole and amphibole rims contain 0.19−4.24 wt.% TiO2, higher than those of amphibole lamellae in the replacive symplectites that varying from 2.38 wt.% TiO2 to below the detection limit. These microstructures were developed during solidification of the intrusion due to the reaction between plagioclase primocrysts and ambient Fe-rich liquid, accompanying with addition of Fe, Ti and Ca and removal of alkalis and silica in an open system. The abundance of such reactive microstructures in the LZ are therefore attributed to silicate liquid immiscibility within a crystal mush, in which the segregation of the buoyant Si-rich component left behind the dense Fe-rich liquid in the lower part of magma chamber. The common presence of amphibole and phlogopite/biotite in the replacive symplectites indicates that continuous fractionation of the Fe-rich liquid leads to hydration of interstitial liquid during the late-stage solidification.

Microstructure and properties of Al−2Mg−0.5Mn alloy with narrow crystallization temperature range realized by adding trace elements

The wide crystallization temperature range of Al−Mg alloys is a key factor for the surface defect formation during continuous casting and rolling process. To reduce the crystallization temperature range of the alloy, the influences of trace Zn, Si, Zr and Ti elements on the microstructure and properties of Al−2Mg−0.5Mn alloy were investigated. The X-ray photoelectron spectroscopy, atomic force microscopy, scanning and transmission electron microscopy were used for microstructural characterization. The Ti and Zr additions could refine the grain size and improve the strength of the Al−Mg−Mn alloy by forming Al3Ti and Al3Zr in the alloy, while the crystallization temperature ranges of these alloys were wider. It was revealed that Zn and Si additions could form new secondary phases with Mg in the alloy, thus reducing the actual Mg content during later eutectic solidification process. Therefore, the crystallization temperature range of Al−2Mg−0.5Mn−0.2Zn−0.2Si alloy was narrower than that of Al−2Mg−0.5Mn alloy. The mechanical properties and corrosion resistance of Al−2Mg−0.5Mn alloy were also improved by the additions of Zn and Si.

Strengthening of CoCrNi medium entropy alloy with Ti additions

A series of (CoCrNi)100-xTix (x = 0, 1.0, 2.0, 3.0 and 4.0) medium entropy alloys (MEAs) was manufactured by high-vacuum arc melting in the present study to examine the effects of Ti additions on the microstructures and mechanical properties of the MEAs. For x = 0, 1.0 and 2.0, the alloys remained a single-phase FCC solid solution. The Ti(Ni, Co)3 precipitates of HCP phase formed for x = 3.0 and 4.0. The presence of Ti, which had the larger atomic radius than the other constituent elements, in the solid solution enhanced the lattice distortion and resulted in grain refinement. The addition of Ti led to the enhanced mechanical properties with the ultimate tensile strength and Vickers hardness increased from 866 MPa and 212 HV at x = 0 to 1490 MPa and 409 HV, respectively, at x = 4.0. The strengthening mechanisms of solid solution strengthening, grain refinement and precipitation strengthening were discussed, and the predicted strengthening was compared with measurements.

Effect of the Ti addition on the corrosion behavior of newly developed AA7075-Ti alloys

In this study, the effect of Ti addition, cold rolling and T6 aging heat treatment on the corrosion behavior of newly produced AA7075–0%Ti, AA7075–2%Ti, AA7075–4%Ti and AA7075–8%Ti quality alloys was investigated. The titanium ratio in the alloys was adjusted using AlTi master alloy in the melting method, and all the alloys produced were subjected to T6 aging heat treatment and some samples were cold rolled at a rate of 6%. The investigation of the immersion and potentiodynamic corrosion behavior of the alloys was conducted in 3.5% by weight of NaCl solution. The corrosion resistance of the alloys studied here is improved by both applied cold rolling and Ti addition. On the other hand, in alloys without Ti addition, the rolling process, which increased the precipitate formation, decreased the corrosion resistance.

Microstructural Evolution and Mechanical Behavior of Co‐Free (Fe40Ni30Cr20Al10)100−xTix High‐Entropy Alloys

In this work, microstructural evolution and mechanical behavior of Co‐free (Fe40Ni30Cr20Al10)100−x Ti x (x = 0, 2, 4, 6, and 8 at%) high‐entropy alloys (HEAs) are investigated. All as‐cast HEAs consist of face‐centered‐cubic (FCC)‐ and body‐centered‐cubic (BCC)‐structured phases, wherein the BCC‐structured phase is composed of disordered BCC (A2) and ordered BCC (B2) phases. The HEAs show FCC dendrite and BCC inter‐dendrite microstructure when x ≤ 4. As the Ti content increases to 6 and 8 at%, the microstructure evolves from dendrite structures to complex lamellar structures, leading to a significant loss in ductility. With the increase of Ti, the strength is enhanced with the sacrifice of ductility. The (Fe40Ni30Cr20Al10)96Ti4 alloy exhibits promising combinations of strength and ductility, displaying a yield strength of 680 MPa, an ultimate tensile strength of 1132 MPa, and a total elongation of 16.6%. The simple FCC + BCC dendrite microstructure and optimal content of the BCC‐structured region containing A2 + B2 phases are responsible for the excellent tensile properties of the as‐cast (Fe40Ni30Cr20Al10)96Ti4 HEA. In this work, it is suggested that good combinations of strength and ductility of low‐cost Co‐free FeNiCrAl‐based HEAs can be achieved by tailoring Ti addition.