Effect Of Li Addition Research Articles

Effects of Li addition on the properties of biodegradable Zn–Fe–Li alloy: Microstructure, mechanical properties, corrosion behavior, and cytocompatibility

Biodegradable Zn-based alloys have excellent mechanical properties, a good corrosion rate, and favorable biocompatibility, which have broad application prospects. In this study, new biodegradable Zn-0.5Fe-xLi (x = 0, 0.2, 0.5, 0.8 wt%) alloys were successively prepared by melting and hot extrusion, and the effects of Li content on the microstructure, mechanical properties, corrosion behavior, and biocompatibility of the alloys were investigated. The formation of FeZn13 and eutectic LiZn4 phases in the Zn-0.5Fe-xLi alloys and the grain size of the Zn-0.5Fe-0.5Li alloys significantly reduced with an increase in Li content. The synergistic effect of solid solution and grain refinement of Li significantly improved the strength of the Zn-0.5Fe-0.5Li alloy and ensured the ductility of the alloy, which resulted in its optimum overall performance. The yield strength was 353.6 ± 6.8 MPa, the ultimate tensile strength was 441.9 ± 2.6 MPa, and the elongation was 26.8 ± 0.8%. In addition, the Zn-0.5Fe-0.5Li alloy showed excellent corrosion properties. The electrochemical corrosion rate was 0.735 mm/year, and the surface corrosion degradation morphology was uniform after immersion. The Zn-0.5Fe-0.5Li alloy also demonstrated the most favorable in vitro cytocompatibility in cellular experiments. Overall, the extruded Zn-0.5Fe-0.5Li alloy is a promising biodegradable implant material with excellent mechanical properties, a suitable corrosion rate, and good cytocompatibility.

Effect of Li addition on bending behavior of extruded Mg–2Zn alloy sheet

The effect of Li element on microstructure and texture evolutions of Mg–2Zn alloy sheet during three-point bending at room temperature were investigated. The results showed that the conventional c-axis//ND basal texture of the extruded Mg–2Zn sheet could be modified to a TD-elongated fiber texture with 3 wt.% Li addition. As a result, the room-temperature bendability of the Mg–2Zn–3Li sheet was improved effectively and this sheet showed a minimum bending radius of only 1.75 mm. Such an excellent bendability exceeds the room-temperature bending capacity of most commercial magnesium alloys. The improvement in bendability of the Mg–2Zn–3Li sheet was attributed to the TD-elongated texture distribution. This type of texture distribution could provide more efficient deformation modes to release the thickness strain during bending compared to the extruded Mg–2Zn sheet. This study could provide insights into developing Mg alloys with high room-temperature bendability by tailoring texture distribution rather than texture weakening.

Effect of Li addition on mechanical properties and ageing precipitation behavior of extruded Al−3.0Mg−0.5Si alloy

Effect of Li addition on mechanical properties and ageing precipitation behavior of extruded Al−3.0Mg−0.5Si alloy

Role of Ln type in the physical mechanisms of defect mediated luminescence of Li, Ln–SnO2 nanoparticles

The effects of Li addition on the luminescence of Ln–SnO2 depend on the Ln type, which are classified as surface (Dy, Tb) and substitutional dopants (Eu, Sm, Er).

Effects of Li addition on the luminescent properties of LiSrPO4:Eu3+ excited with X-ray and ultraviolet radiation

Abstract Li1+xSr0.99PO4:Eu0.01 (x = 0.1, 0.3 or 0.5) phosphors are prepared using glucose with a modified sol-gel method. X-ray diffraction (XRD), scanning electron microscopy and photoluminescence and X-ray absorption spectroscopy are used to characterize the structural and optical behaviour of the phosphors. LSPOE powders have been successfully synthesized by sol-gel route and confirmed by XRD. A variation in lithium stoichiometry does not contribute to significant changes in structural properties, as probed by XRD. The samples have a partially spherical morphology with a high degree of particle agglomeration. The emission intensity of Eu3+ varies with the increase in Li+ content, in agreement with the variation of the symmetric factor. This behaviour verifies that the Eu3+ ion is in a site of low symmetry. The X-ray absorption near edge structure results reveal that the reduction of Eu3+ to Eu2+ is induced by ionising radiation and the intensity of the X-ray excited optical luminescence emission is inversely proportional to the concentration of lithium.

Studies on Pitting Corrosion of Al-Cu-Li Alloys Part I: Effect of Li Addition by Microstructural, Electrochemical, In-situ, and Pit Depth Analysis.

To analyze the effect of lithium and microstructure on the pitting corrosion behavior of aluminum alloys, three types of aluminum alloys were studied via scanning electron microscopy, transmission electron microscopy, electrochemical polarization, and by immersion tests coupled with in-situ observation of pitting and statistical analysis of pit depths measured by surface profilometry. It was found that, with increasing lithium content, the resistance to pitting corrosion was enhanced and the passive range was enlarged. In-situ observation revealed that the development of pitting corrosion exhibited three stages, including an initial slow nucleation stage (Stage I), a fast development stage (Stage II), and a stabilized growth stage (Stage III). Higher lithium content contributed to shorter time periods of Stages I and II, resulting in faster pitting evolution and a higher number of pits. However, the pits were generally shallower for the specimen with the highest lithium content, which is in agreement with the results of the electrochemical analysis.

Effects of Li addition on the corrosion behaviour and biocompatibility of Mg(Li)–Zn–Ca metallic glasses

Magnesium alloys with suitable corrosion behaviour and good mechanical properties are desired for biodegradable materials. In the current study, novel Mg–Li-based metallic glasses (MGs) demonstrate potential clinical applications as implantable biodegradable materials. The amorphous structure of MGs provides suitable elastic modulus with human bone. The enhanced corrosion resistance of MGs realises a uniform corrosion process, as well as maintains a stable acid-based environment, and increases cell proliferation. A schematic model is proposed to illustrate the corrosion mechanisms of MGs. Adding Li significantly improves the corrosion resistance of MGs. Both the indirect cytotoxicity and direct cell culture assays are conducted using transfected osteoblasts (hFOB) cells. Results show that the novel Mg–Li–Zn–Ca MGs have good biocompatibility.

First-Principles Studies on Twinnability of Magnesium Alloys: Effects of Yttrium and Lithium on $$\left( {10\bar{1}1} \right)\left[ {\bar{1}012} \right]$$ 10 1 ¯ 1 1 ¯ 012 Compression Twinning Deformation Processes

We investigate the energetics involved in the $$\left( {10\bar{1}2} \right)\left[ {\bar{1}011} \right]$$ tension and $$\left( {10\bar{1}1} \right)\left[ {\bar{1}012} \right]$$ compression twinning deformation processes in magnesium via first-principles studies. Through identification of structural changes associated with each deformation process, we study the energetics of each deformation process and the local instability in the twin boundary region. We observe that the energy barrier in the $$\left( {10\bar{1}1} \right)\left[ {\bar{1}012} \right]$$ compression twinning deformation pathway is higher than that in the $$\left( {10\bar{1}2} \right)\left[ {\bar{1}011} \right]$$ tension twinning deformation pathway, even though the $$\left( {10\bar{1}1} \right)$$ compression twin boundary is more stable than the $$\left( {10\bar{1}2} \right)$$ tension twin boundary. We extend our study to examine the effects of Y and Li as alloying elements on each twinning deformation process. Our calculations predict that the addition of Y causes a reduction in the probability of fracture by an order of magnitude when the twinning deformation occurs and weakening of the resistivity to twinning deformation. However, the effect of Li addition on the twinning deformations is weaker than that of Y addition.

Effect of Li Addition on the Optimum Thermo-Mechanical Processing Parameters of the Mg Alloy AZ31

The effect of minor additions of Li on the high-temperature workability of AZ31 Mg alloy is assessed using the processing maps approach. Data obtained from the uniaxial compression tests that were performed over the temperature, T, range of 523 K to 673 K (250 °C to 400 °C) and strain rate, $$ \dot{\varepsilon } $$ , range of 10−3 to 10+1 s−1 was utilized to construct the power dissipation and instability maps using modified dynamic material model proposed by Murty and Rao. These maps and complementary microstructural analyses were utilized to identify various deformation mechanisms that operate in different T- $$ \dot{\varepsilon } $$ regime. For the base 0Li alloy, two distinct deformation domains were identified, in both of which dynamic recrystallization (DRX) is the operating deformation mechanism. The addition of 1 wt pct Li extends Domain I to higher T and Domain II to higher $$ \dot{\varepsilon } $$ , both with enhanced power dissipation efficiency. On the other hand, higher Li-containing alloys exhibit one wide single domain over the entire T range of 523 K to 673 K (250 °C to 400 °C) and $$ \dot{\varepsilon } $$ of 10−2.5 to 10+0 s−1 with power dissipation efficiency varying from 20 to 70 pct. The optimum T- $$ \dot{\varepsilon } $$ combination for the high-temperature deformation of these alloys in homogenized condition is 623 K to 673 K (350 °C to 400 °C) and 10+0.5 to 10+0 s−1, where DRX occurs. Microstructural analysis indicates that Li addition in AZ31 suppresses DRX at low $$ \dot{\varepsilon } $$ and promotes dynamic recovery though cross-slip. Instability maps corroborated with microstructural analysis showed flow instabilities in the form of shear bands and cracking along grain boundaries.

Effect of Li addition on the formation of Na-β/βʹʹ-alumina film by laser chemical vapor deposition

Films composed of a mixture of Na-β- and βʹʹ aluminas (β/βʹʹ-alumina) were prepared via laser chemical vapor deposition (CVD) upon the addition of Li. The effect of the Li source gas on the phase formation, microstructure and deposition rates of the β/βʹʹ-alumina films was investigated. The Na-β/βʹʹ-alumina films were formed at a Li/Al precursor supply ratio (RLi/Al) of 0.1–1.0 within a deposition temperature (Tdep) range of 1100–1220K. The Na-β/βʹʹ-alumina phase was exclusively formed at Tdep=1165–1185K and RLi/Al=0.1–0.5, whereas α-Al2O3 (with minor amounts of LiAlO2 and LiAl5O8) was predominantly observed at Tdep>1223K and RLi/Al >1.0. The Na-β/βʹʹ-alumina films were composed of polygonal facets in sizes of several hundred nanometers with a columnar cross section. The deposition rate of the Na-β/βʹʹ-alumina film was 60µmh−1.

Effect of Li addition on the plastic deformation behaviour of AZ31 magnesium alloy

The enhancement in the workability, if any, of a dilute Mg alloy, AZ31, with the Li addition is investigated by examining the hot deformation behaviour of AZ31 alloyed with 1, 3 and 5wt% Li. Compression tests were conducted in the temperature, T, range of 150–400°C and strain rates, ε̇, ranging from 10−3 to 10+2s−1. Experimental results show that the deformation behaviour can be divided into three T regimes. In the low T regime (150–200°C), an increase in the Li content in AZ31 decreases the twin density with a concomitant enhancement in the non-basal or cross-slip activity. While high Li alloys exhibit low flow stress at low ε̇ in this regime, an increase in ε̇ increases strain hardening rate and twinning activity. Flow localization and shear band formation were observed in most of the alloys in this regime. Deformation in the intermediate T regime (250–300°C) leads to dynamic recovery (DRY) at low ε̇ and dynamic recrystallization (DRX) at high ε̇, which are the softening mechanisms in Li containing alloys. In high T regime (350–400°C), these alloys exhibit softening mechanisms similar to intermediate T regime but high Li alloys surprisingly exhibit higher flow stresses, which is attributed to the higher amount of Li in the solid solution, a result of the dissolution of Li containing precipitates. Non-basal slip and twinning at high ε̇ occur uniformly with homogeneous DRX. A low activation energy for deformation of high Li alloys indicates that the Friedel-Escaig (F-E) mechanism as the rate controlling deformation mechanism. The onset of twinning was examined by the appearance of first local maxima before peak strain in (d2σ/dε2) vs. ε curves. Mechanisms responsible for the dependence of critical stress for the onset of DRX on T and ε̇ are also discussed.

Effects of Li addition on microstructure and mechanical properties of Mg–6Al–2Sn–0.4Mn alloys

Effects of Li addition (2%, 5%, 8% and 11%) on microstructure and mechanical properties of the as-cast and as-extruded Mg–6Al–2Sn–0.4Mn-based alloys were investigated. Mg–xLi–6Al–2Sn–0.4Mn (x= 2, 5, 8 and 11, mass fraction, %) alloys were cast under an SF6 and CO2 atmosphere at 700 °C. After homogenization heat treatment at 350 °C, cast billets were extruded with a reduction ratio of 40:1 at 200 °C. Li addition to Mg–6Al–2Sn–0.4Mn resulted in the formation of MgSnLi2 and MgAlLi2 and/or AlLi intermetallic compounds and random basal texture. With increasing Li addition, β-Li phase was increased and the average area fraction of precipitates increased. Compression yield strength was increased from 212 to 235, 242 and 239 MPa as Li content was increased from 2% to 5%, 8% and 11%, respectively. Elongation was remarkably increased above 60% in 11% Li alloy. It is probable that Li-containing phases play a significant role in the enhanced mechanical properties by Li addition.

Structural transition region of liquid Mg–Li alloys

The local structural, dynamical, and thermodynamic properties of liquid Mg–Li alloys at 973K have been investigated using ab initio molecular dynamics simulation. The calculated pair-correlation functions agree well with the experimental results for pure Mg and Li. The local atomic structures have been characterized by the coordination number, bonded pair, and Voronoi polyhedron analysis. A structural transition region is found in the composition range from 12.5at.% Li to 31.25at.% Li: the close packing local atomic structures begin to transform to bcc type, which are dominated by the structural changes around Mg atoms on the effect of Li addition. The inflection point of calculated mixing enthalpy curve is also located in this region, supporting the transition of local atomic structures. Owing to the structural transition, the self-diffusion coefficients of Mg and Li change with different tendencies as Li content increasing. In addition, the interaction between Mg and Li atoms is evaluated by the quantity of charge transfer in liquid Mg–Li alloys. According to the quasi-chemical approximation model, charge transfer is confirmed as the key-factor of interaction energy.

B22-P-07Structural Analysis of Au Doped Titanium Disilicide using Cs-corrected Scanning Transmission Electron Microscopy

Al-Mg-Si-based alloys are widely used and studied due to the increasing demand of reducing weight of automobile body panels. One of the main topics in the studies is improvement of the hardening response in the initial stage of artificial aging. Recently, Koshino et al. reported that 0.04 wt.% addition of Li increases the hardness of an Al-Mg-Si alloy aged for not only 10 hours (peak aging) but also 20 minutes (under-aging) due to the co-segregation among Mg, Si and Li atoms [1]. The results had been predicted by early works [2, 3]. However, the effect of Li addition on microstructure evolution is not well understood. In this work, we conducted 3DAP analyses of a base alloy (Al-0.62Mg-0.93Si, wt.%) and a Li-added alloy (Al-0.55Mg-0.89Si-0.05Li, wt.%) aged at room temperature for 300 and 2100 hours. It was found that the Li-addition increases the number density of clusters which consist of mainly Mg and Si atoms. Further analyses were performed for the Li-added alloys to clarify the positional correlation between Li atoms and the clusters. Although it is difficult to judge the correlation visually as shown in Figure, co-segregation among Mg, Si and Li atoms was confirmed by applying statistical techniques.The detail of the analysis process will show in the presentation to discuss its superiority and limitation. [1] Y. Koshino, M. Kozuka, S. Hirosawa and Y. Aruga, J. Alloy Compd. 622 (2015) 765-770. [2] T. Sato, S. Hirosawa, K. Hirose and T. Maeguchi, Metall. Mater. Trans. A 34 (2003) 2745-2755. [3] S. Hirosawa, T. Omura, Y. Suzuki and T. Sato, Mater. Sci. Forum 215 (2006) 519-521. Figure: (a) Li, (b) Mg and (c) Si map of Al-Mg-Si-Li alloy aged at room temperature for 2100 hours. B22-P-07 doi:10.1093/jmicro/dfv263

Modified texture and room temperature formability of magnesium alloy sheet by Li addition

The effect of Li addition on the mechanical responses of magnesium alloy sheets was examined in correlation with the concurrent microstructure and texture evolution. The basal texture was drastically weakened and the basal pole rotated to the transverse direction (TD) owing to the Li addition. The Mg alloy sheet containing lithium element exhibited larger uniform elongation and its Erichsen value (IE) increased by ~ 59 %. Enhanced the ambient formability of the extruded Mg alloy sheet fabricated by Li addition was accomplished by the tilted weak basal texture. The microstructure evolution and properties were characterized and compared.

Effect of Li addition on microstructure and mechanical properties of Al – Mg – Si alloy

Abstract The ever increasing utilization of Al – Li alloys for light weight structural applications is limited chiefly due to their lower room temperature formability compared to their Li-free counterparts. In the present work, the effect of 1, 2 and 3 wt.% Li addition to Al – Mg – Si alloy (containing 0.5 wt.% Mg and 0.2 wt.% Si) was studied. Experimental work showed that microstructural features of the second phase particles and mechanical properties changed substantially with Li addition. It was observed that 1 wt.% Li addition resulted in significantly large elongation of over 38 % resembling a super-plastic behavior with decent strength and hardness due to the formation of second phase precipitates uniformly dispersed in α (Al) matrix. Scanning electron microscopy and X-ray diffraction analysis revealed that the addition of Li promotes the formation of second phase precipitates, which strongly affect the mechanical properties of Al – Mg – Si alloy. Quite surprisingly, the alloys containing 2 and 3 wt.% Li showed a much reduced ductility and a much higher hardness after aging.

Microstructure and mechanical properties of Mg–xLi–3Al–1Sn–0.4Mn alloys (x=5, 8 and 11wt%)

Abstract Effects of Li addition on microstructure and mechanical properties of as-cast and as-extruded Mg–xLi–3Al–1Sn–0.4Mn alloys were investigated. Mg–3 wt%Al–1 wt%Sn–0.4 wt%Mn alloys with different Li addition (5, 8 and 11 wt%) were cast under an SF6 and CO2 atmosphere at 700 °C and extruded at 200 °C. Li addition to Mg–3Al–1Sn–0.4Mn resulted in the formation of MgLi2Sn and MgLi2Al intermetallic compounds and random basal texture. With increasing Li addition from 5 to 8 and 11 wt%, ultimate tensile strength was decreased from 258 to 240 and 220 MPa. On the other hand, the elongation was improved remarkably from 16.0% to 15.4% and 35.1% at room temperature due to transformation from HCP to BCC crystal structure and a weaker basal texture. In the Mg–xLi–3Al–1Sn–0.4Mn alloys, MgLi2Sn and MgLi2Al intermetallic compounds played a significant role for the increase of the mechanical properties.

Effects of Li addition on the microstructure and mechanical properties of Mg–3Zn–1Sn–0.4Mn based alloys

In this work, Mg–3wt%Zn–1wt%Sn–0.4wt%Mn alloys with different Li addition (5, 8 and 11wt%) were melted and extruded at 200°C. Effects of Li addition on microstructure and mechanical properties of as-cast and as-extruded Mg–xLi–3Zn–1Sn–0.4Mn alloys were investigated. Li addition to Mg–3Zn–1Sn–0.4Mn based alloy resulted in the formation of MgLi2Sn intermetallic compound. By Li addition from 5wt% to 8 and 11wt%, the ductility was significantly increased from 18.1% to 30.9% and 49.3% at room temperature due to transformation from HCP to BCC crystal structure and formation of a weaker basal texture of the α-Mg phase region. The ultimate tensile strength (UTS) was decreased from 252.0, 201.1 and 148.7MPa as Li content increased from 5 to 8 and 11wt%. On the other hand, the tensile strength of Sn containing alloys was remarkably increased compared to the alloys without Sn addition due to the presence of the fine MgLi2Sn intermetallic compounds.

Effect of Li addition on the mechanical behavior and texture of the as-extruded AZ31 magnesium alloy

Lithium alloying additions are verified to be an effective way to enhance the room temperature formability of magnesium. In this work, AZ31 (Mg–3wt% Al–1wt% Zn) alloys with different lithium additions (0–5wt%) were melted and extruded to 2mm thick sheets at 380°C. The microstructure and texture evolution were investigated by optical microscopy, X-ray diffraction (XRD) and electronic backscattered diffraction (EBSD). Tensile tests along three directions were carried out at room temperature, to access the mechanical properties and anisotropy. It was found that the mechanical anisotropy of the as-extruded AZ31 alloy was modified remarkably with lithium additions and AZ31 alloy with 5% Li content was found to have the smallest planar anisotropy and enhanced elongation. Lithium additions also increased the rotation of basal poles in the transverse direction, which was attributed to decreased c/a ratio and refined recrystallized structure. The thickness reduction and width reduction during tensile test were also measured and discussed.

Effect of Li addition on phase formation behavior and electrical properties of (K 0.5Na 0.5)NbO 3 lead free ceramics

In this work, Li-modified KNN ceramic compositions ((K 0.5Na 0.5) 1− x Li x )NbO 3 with x = 0.03, 0.04, 0.05, 0.06, 0.65 and 0.07 were prepared by a conventional solid-state mixed-oxide method. The structural phase formation and microstructure were characterized by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM). It has been found that a morphotropic phase boundary (MPB) between orthorhombic phase and tetragonal phases should exist between compositions with Li contents of 6–6.5%. The Curie temperature ( T c) of the ceramics shifted to higher temperature with increasing Li content. The room temperature dielectric constant was also seen to be higher than the pure KNN ceramics. In addition, the ferroelectric properties were found to enhance at near MPB compositions. This study clearly showed that the addition of Li could improve the dielectric and ferroelectric properties in (K 0.5Na 0.5)NbO 3 ceramics.