Rod-shaped Particles Research Articles

Isolation of Antibacterial Nano-Hydroxyapatite Biomaterial from Waste Buffalo Bone and Its Characterization

Hydroxyapatite nanoparticles were isolated from a biowaste, buffalo bone, via the thermal decomposition method. The resulting white powdered material was characterized by Fourier Transformed Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) analysis. The FTIR spectra confirmed that a heat treatment of the bone powder at the temperature at or above 1223 K removed the organic moieties leading to the formation of a pure inorganic biomineral. The XRD analyses showed that the obtained material was nanocrystalline HAp (nano-HAp) with an average grain diameter of 25 nm, while their rod-shaped particles with their tightly agglomerated morphology were confirmed by the SEM analysis. Besides Calcium (Ca), Phosphorous (P), and Oxygen (O), trace amounts of Aluminum (Al), Magnesium (Mg), Copper (Cu), Zirconium (Zr) and Carbon (C) were also found by EDX analysis. Antibacterial activity of nano-HAp against six standard isolates was investigated by the agar well diffusion method and found to be more susceptible to Acinetobacter baumannii while other standard strains such as Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus showed lesser susceptibility and no antibacterial activity was noticed against Salmonella typhi and Methicillin resistant Staphylococcus aureus (MRSA) with the analysed concentration of nano-HAp suggesting its potential application in biomedical fields.

Surface Functionalization of Rod-Shaped Viral Particles for Biomedical Applications.

While synthetic nanoparticles play a very important role in modern medicine, concerns regarding toxicity, sustainability, stability, and dispersity are drawing increasing attention to naturally derived alternatives. Rod-shaped plant viruses and virus-like particles (VLPs) are biological nanoparticles with powerful advantages such as biocompatibility, tunable size and aspect ratio, monodispersity, and multivalency. These properties facilitate controlled biodistribution and tissue targeting for powerful applications in medicine. Ongoing research efforts focus on functionalizing or otherwise engineering these structures for a myriad of applications, including vaccines, imaging, and drug delivery. These include chemical and biological strategies for conjugation to small molecule chemical dyes, drugs, metals, polymers, peptides, proteins, carbohydrates, and nucleic acids. Many strategies are available and vary greatly in efficiency, modularity, selectivity, and simplicity. This review provides a comprehensive summary of VLP functionalization approaches while highlighting biomedically relevant examples. Limitations of current strategies and opportunities for further advancement will also be discussed.

Coarsening kinetics of Cu particles in an Fe-1.5% Cu alloy

Abstract The Ostwald ripening of spherical and rod-shaped Cu precipitate particles in an Fe-1.5 mass% Cu alloy aged between 873 and 1023 K has been examined by measuring both the particle size by electron microscopy and the Cu concentration in the α-Fe matrix by electrical resistivity. The average radius of spherical and rod-shaped particles increases with ageing time t as t 1/3, in agreement with the growth by diffusion-controlled coarsening. The kinetics of the depletion of supersaturation with t obey the predicted t – 1/3 time law. The Cu/α-Fe interfacial energy and the diffusivity of Cu in α-Fe have been independently derived from the data on coarsening. The interfacial energies are measured as 0.57 and 1.1 Jm–2 for the spherical and rod-shaped particles respectively. The pre-exponential factor and the activation energy for bulk diffusion are found to be 4.54α10 –5 m2s– 1 and 241 kJmol – 1.

Investigation on antibacterial activity of α-Fe2O3 / ZnO nanocomposites against Gram-positive and Gram-negative bacteria

ABSTRACT In this study, α-Fe2O3/ZnO nanocomposites were synthesized by co-precipitation and solvothermal methods. The morphology, structure, and properties were characterized by FTIR, XRD, FESEM, EDS, and TEM techniques. The XRD patterns showed that the nanocomposite included rhombohedral haematite (α-Fe2O3), hexagonal zincite (ZnO), and cubic franklinite (ZnFe2O4). TEM images revealed the formation of rod-shaped particles with an average diameter of 18 nm and length of 125.82 nm. The quantity of Fe, Zn, and O was obtained to be 12.92%, 9.26%, and 77.82%, respectively. To investigate the effect of the zinc oxide concentration on antibacterial properties, α-Fe2O3/ZnO nanocomposite FZ0.5, FZ1.5, and FZ2.5 were prepared. The antibacterial properties against Staphylococcus aureus, and Escherichia coli bacteria were investigated. α-Fe2O3/ZnO had an efficient antibacterial activity on Gram-positive bacterial strains, and nanocomposites with higher zinc levels demonstrated a more efficient antibacterial activity. The effect of calcination temperature on the antibacterial activity of the sample was also studied .

Anisotropic Rod-Shaped Particles Influence Injectable Granular Hydrogel Properties and Cell Invasion.

Granular hydrogels have emerged as a new class of injectable and porous biomaterials that improve integration with host tissue when compared to solid hydrogels. Granular hydrogels are typically prepared using spherical particles and this study considers whether particle shape (i.e., isotropic spheres vs anisotropic rods) influences granular hydrogel properties and cellular invasion. Simulations predict that anisotropic rods influence pore shape and interconnectivity, as well as bead transport through granular assemblies. Photo-cross-linkable norbornene-modified hyaluronic acid is used to produce spherical and rod-shaped particles using microfluidic droplet generators and formed into shear-thinning and self-healing granular hydrogels, with particle shape influencing mechanics and injectability. Rod-shaped particles form granular hydrogels that have anisotropic and interconnected pores, with pore size and number influenced by particle shape and degree of packing. Robust invitro sprouting of endothelial cells from embedded cellular spheroids is observed with rod-shaped particles, including higher sprouting densities and sprout lengths when compared to hydrogels with spherical particles. Cell and vessel invasion into granular hydrogels when injected subcutaneously in vivo are significantly greater with rod-shaped particles, whereas a gradient of cellularity is observed with spherical particles. Overall, this work demonstrates potentially superior functional properties of granular hydrogels with rod-shaped particles for tissue repair.

Effect of mechanically modification process on boron carbide synthesis from polymeric precursor method

In this study, a polymeric precursor was synthesized from industrial raw materials by the sol-gel method. The organic components in the polymeric chain structure were separated with the calcination process, and a reactant consisting of carbon and B2O3 was obtained. Mechanically modification process was applied to the reactant by a ball milling, which changed the structure of the reactant. It was observed that this process promoted the crystallinity and decreased the particle size of the reactant. In addition, the bimodal structure of the reactant was transformed to a bicontinuous structure. The reactant and a mechanically modified carbon-based reactant (MMCBR) were applied to heat treatment at 1400–1700 °C for 5 h under argon gas to investigate the effect of mechanically modification process on final products. A non-uniform powder morphology with polyhedral and rod-shaped B4C particles was obtained from reactant and MMCBR. While the B4C powder obtained from the reactant was agglomerated, no agglomeration was observed at the B4C powder obtained from MMCBR. As a result, the B4C powder synthesized in this fashion contained less free carbon as compared to that prepared with MMCBR.

Formation of single-crystalline BaTiO3 nanorods from glycolate by tuning the supersaturation conditions

We have studied peculiarities in the formation of single-crystalline barium titanate (BaTiO3) nanorods from a glycolate-mediated complex via a single-step hydrothermal process under different supersaturation (SR) conditions. X-ray diffraction (XRD) showed the formation of pure BaTiO3 with an SR of above 19. The tetragonality for the BaTiO3 (c/a) reached 1.013 at SR = 19–29 and dropped to 1.010 for SR = 39. According to the transmission electron microscopy (TEM) and XRD analyses, the rod-shaped particles exhibited single crystallinity and crystal growth along the [001] plane. With scanning electron microscopy (SEM), the morphological evolution from a plate-shaped intermediate precursor (SR = 6–9) to a rod-shaped product with an aspect ratio of 6–9 (SR = 19–29), and to non-polar material with an irregular structure (SR = 39), was observed. The negative slope, linear dependence of the particles’ width and length on the supersaturation level in the range SR = 19–39 was established for the first time. The replacement of the prevailing crystallization mechanism from in-situ topotactic transformation into dissolution-precipitation above SR = 19 was observed. It was shown that with a simple regulation of the SR, the structural and morphological characteristics of the obtained BaTiO3 nanoparticle can be effectively tuned.

Reconfigurable label-free shape-sieving of submicron particles in paired chalcogenide waveguides.

Up-to-date particle sieving schemes face formidable challenges for sieving label-free submicron molecules with similar sizes and dielectric constants but diverse shapes. Herein, optical sorting of polystyrene particles with various shapes is illustrated in optofluidic nanophotonic paired waveguide (ONPW) composed of chalcogenide semiconductor Sb2Se3. The Sb2Se3-ONPW creates the coupling length (CL) between the neighboring hot spots that can be actively modulated via the transition of Sb2Se3 between amorphous (AM) and crystalline (CR) phases. Submicron particles interfere with the coupled hotspots, which can exert various optical torques on the particles according to their profiles. In the model system, spherical (diameter of 0.5 μm) and rod-shaped (diameter of 0.5 μm, length of 1.5 μm) polystyrene particles were employed to mimic two types of bacteria, namely, Staphylococcus aureus and rod-shaped Escherichia coli, respectively. For the AM state, the CL value is ∼7.0 μm, enabling the structure to trap the sphere stably in the hot spots. For the CR state, the CL value becomes ∼25 μm, leading to stable trapping of the rod-shaped particle. In this work, the working wavelength was fixed at 1.55 μm at which both AM- and CR-Sb2Se3 are transparent. Our scheme may offer a paradigm shift in shape-selective sieving of biomolecules and fulfill the requirements of the new-generation lab-on-chip techniques, where the integrated manipulation system must be much more multifunctional and flexible.

Self-assembly of berberine and a boron cluster for antibacterial regulation

B12H122−and BBR can quickly form rod-shaped particles in aqueous solution with enhanced reactive oxygen species (ROS) generation ability.

Bioevaluation of magnetic mesoporous silica rods: cytotoxicity, cell uptake and biodistribution in zebrafish and rodents.

Mesoporous silica nanoparticles (MSN) characterized by large surface area, pore volume, tunable chemistry, and biocompatibility have been widely studied in nanomedicine as imaging and therapeutic carriers. Most of these studies focused on spherical particles. In contrast, mesoporous silica rods (MSR) that are more challenging to prepare have been less investigated in terms of toxicity, cellular uptake, or biodistribution. Interestingly, previous studies showed that silica rods penetrate fibrous tissues or mucus layers more efficiently than their spherical counterparts. Recently, we reported the synthesis of MSR with distinct aspect ratios and validated their use in multiple imaging modalities by loading the pores with maghemite nanocrystals and functionalizing the silica surface with green and red fluorophores. Herein, based on an initial hypothesis of high liver accumulation of the MSR and a future vision that they could be used for early diagnosis or therapy in fibrotic liver diseases; the cytotoxicity and cellular uptake of MSR were assessed in zebrafish liver (ZFL) cells and the in vivo safety and biodistribution was investigated via fluorescence molecular imaging (FMI) and magnetic resonance imaging (MRI) employing zebrafish larvae and rodents. The selection of these animal models was prompted by the well-established fatty diet protocols inducing fibrotic liver in zebrafish or rodents that serve to investigate highly prevalent liver conditions such as non-alcoholic fatty liver disease (NAFLD). Our study demonstrated that magnetic MSR do not cause cytotoxicity in ZFL cells regardless of the rods' length and surface charge (for concentrations up to 50 μg ml-1, 6 h) and that MSR are taken up by the ZFL cells in large amounts despite their length of ∼1 μm. In zebrafish larvae, it was observed that they could be safely exposed to high MSR concentrations (up to 1 mg ml-1 for 96 h) and that the rods pass through the liver without causing toxicity. The high accumulation of MSR in rodents' livers at short post-injection times (20% of the administered dose) was confirmed by both FMI and MRI, highlighting the utility of the MSR for liver imaging by both techniques. Our results could open new avenues for the use of rod-shaped silica particles in the diagnosis of pathological liver conditions.

On the growth of the soft and hard protein corona of mesoporous silica particles with varying morphology

The characterization of the protein corona has become an essential part of understanding the biological properties of nanomaterials. This is also important in the case of mesoporous silica particles intended for use as drug delivery excipients. A combination of scattering, imaging and protein characterization techniques is used here to assess the effect of particle shape and growth of the reversible (soft) and strongly bound (hard) corona of three types mesoporous silica particles with different aspect ratios. Notable differences in the protein composition, surface coverage and particle agglomeration of the protein corona-particle complex point to specific protein adsorption profiles highly dependent on exposed facets and aspect ratio. Spherical particles form relatively homogeneous soft and hard protein coronas (approx.10 nm thick) with higher albumin content. In contrast to rod-shaped and faceted particles, which possess soft coronas weakly bound to the external surface and influenced to a greater extent by the particle morphology. These differences are likely important contributors to observed changes in biological properties, such as cell viability and immunological behaviour, with mesoporous silica particle shape.

Synthesis and Characterisation of Indium Tin Oxide Thin Films for Dye-Sensitised Solar Cells using Natural Fruit Extracts

The study focuses on the application of natural fruit extract of blackberry in dye-sensitised solar cells (DSSC) as a photosensitiser. The widespread availability of the fruits and juices, high concentration of anthocyanins in them ease of extraction of anthocyanin dyes from these commonly available fruits, enable them as a novel and inexpensive candidates for solar cell fabrication. Anthocyanins are naturally occurring biodegradable and non-toxic compounds that can be extracted with minimal environmental impact and provide environmentally benign alternatives for manufacturing dyes in DSSC synthesis. Indium tin oxide (ITO) thin films are synthesised using sol-gel and spin-coating techniques. ITO characteristics are determined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared spectra (FTIR) measurements. To find the transmittance percentage in the visible region of thin films, atomic force microscope (AFM) and UV-Vis spectroscopy analyses were done. The nanocrystalline phase of the synthesised ITO films was confirmed through XRD. SEM was used to analyse the morphology of the synthesised ITO films. Cubic, columnar (edge length ~ 35-45 nm) and rod-shaped (~110 x 14) particles were observed. Narrow size distribution was observed for spherical particles in the range of ~13-15 nm. The FTIR analysis revealed the presence of carboxyl and hydroxide functional groups. The AFM analysis revealed the uniform spread of the synthesised dye, while the visible region absorbance and transmittance of the synthesised ITO films were confirmed through UV-vis spectroscopy. The thin films showed 83-86% of average transmittance. Finally, we fabricated a dye-sensitised solar cell with desired properties. The characterisation results confirmed that the synthesised material could be used in the DSSC application.

Soft-templating routes for the synthesis of mesoporous tantalum phosphates and their catalytic activity in glycerol dehydration and carbonylation reactions

The craftsmanship in catalyst synthesis becomes very fascinating when the catalytic activity of the material can be enhanced by tuning the synthesis conditions. The underlying fundamental strategy is presented here in tailoring the structural and chemical behavior of the tantalum phosphates (TaP) by using different structure directing agents (SDAs). We found that by employing appropriate template assisted pathway it is possible to tune the morphology and the nature of active sites of TaP. The synthesised catalysts were comprehensively characterised by N2-physisorption, FESEM, HRTEM, powder XRD, FTIR, UV–Vis, XPS, NH3 and CO2-TPD, Py-adsorbed IR, elemental analysis and 31P{1H} NMR techniques. The FESEM and HRTEM analysis revealed the transition of non-spherical to rod-shaped particles upon moving from ionic to non-ionic surfactants. The TPD and Py-IR studies revealed the variation in amount, strength and nature of the acidic-basic sites with the change in SDA. The resultant TaP catalysts were investigated for gas phase glycerol dehydration to acrolein and liquid phase glycerol carbonylation to glycerol carbonate. Among these catalysts, TaPC synthesized by using CTAB as SDA exhibited promising catalytic activity in both gas and liquid phase reactions. The active site elucidation in TaPC catalyst was done by adopting basic probe molecule 2,6-lutidine. The deactivation kinetic study was carried out for the gas phase glycerol dehydration reaction. The investigation on the spent catalyst showed it is stable under both gas-phase and liquid-phase reaction conditions. This study hence provides a pathway for analytical architecture and construction of highly efficient TaP catalysts for glycerol transformation reactions.

Microstructure and mechanical property evolution of additive manufactured eutectic Al-2Fe alloy during solidification and aging

This study presents the microstructure and mechanical properties of an additive manufactured recyclable Al-2Fe alloy fabricated by laser powder bed fusion (LPBF). The microstructure evolution of the Al-2Fe alloy aged at elevated temperatures and its impact on the mechanical properties were systematically investigated. Firstly, the single melt scanning experiment verified that Al-Al6Fe anomalous eutectic structure was initially formed from the liquid phase. Secondly, the as-built Al-2Fe contains nano-size and rod-shaped Al6Fe particles which uniformly dispersed in a supersaturated Al matrix. The Al6Fe particles with an average diameter of ~89 nm shows a coherent crystallographic relationship with the matrix as (046)Al6Fe // (2¯02¯)Al, and [032¯]Al6Fe // [1¯11]Al. The ultimate tensile strength and total elongation of 287.0 MPa and 12.0% were obtained in the ultrafine as-built Al-2Fe, respectively. Aging at elevated temperatures made the Al6Fe particles coarsened and transformed into Al13Fe4 particles at 350 °C. The amount of the total Al-Fe intermetallic compounds (Al6Fe+Al13Fe4) increased with the aging temperature due to the precipitation of the supersaturated Fe atoms. It exhibits a slow increase in grain size and a decrease in dislocation density in the Al-2Fe samples with the increase of aging temperature. All Al6Fe particles were transformed into coarse Al13Fe4 particles at 550 °C. Thirdly, the quantitative analysis indicates that the dominant contribution to the yield strength derives from the dispersion strengthening mechanism by creation of fine Al6Fe and Al13Fe4 particles. The results in this work demonstrate that ultrafine microstructure can be obtained in a simple binary Al-Fe alloy as a result of the extremely high cooling rate during LPBF process, which offers a design strategy towards high-strength recyclable aluminum alloys.

Characterization of gliadin, secalin and hordein fractions using analytical techniques

Prolamins, alcohol soluble storage proteins of the Triticeae tribe of Gramineae family, are known as gliadin, secalin and hordein in wheat, rye and barley respectively. Prolamins were extracted from fifteen cultivars using DuPont protocol to study their physiochemical, morphological and structural characteristics. SDS-PAGE of prolamins showed well resolved low molecular weight proteins with significant amount of albumin and globulin as cross-contaminant. The β-sheet (32.72–37.41%) and β-turn (30.36–37.91%) were found higher in gliadins, while α-helix (20.32–28.95%) and random coil (9.05–10.28%) in hordeins. The high colloidal stability as depicted by zeta-potential was observed in gliadins (23.5–27.0 mV) followed secalins (11.2–16.6 mV) and hordeins (4.1–7.8 mV). Surface morphology by SEM illustrated the globular particle arrangement in gliadins, sheet like arrangement in secalins and stacked flaky particle arrangement in hordeins fraction. TEM studies showed that secalin and hordein fractions were globular in shape while gliadins in addition to globular structure also possessed rod-shaped particle arrangement. XRD pattern of prolamin fractions showed the ordered crystalline domain at 2θ values of 44.1°, 37.8° and 10.4°. The extracted prolamins fractions showed amorphous as well as crystalline structures as revealed by XRD and TEM analysis. Space saving hexagonal molecular symmetry was also observed in TEM molecular arrangement of prolamins which has profound application in development of plant-based polymers and fibres.

Microstructure-optimized concentration-gradient NCM cathode for long-life Li-ion batteries

Herein, a comprehensive investigation of the effect of calcination temperature on the physicochemical properties of full-concentration-gradient Li[Ni0.78Co0.10Mn0.12]O2 (FCG NCM78) and the electrochemical performance of FCG NCM78 cathodes was conducted. The electrochemical performance of the FCG NCM78 cathode was significantly influenced by the physical properties of FCG NCM78, such as crystallinity, compositional gradient, and morphology. The crystallinity of FCG NCM78 increased with increasing calcination temperature; however, the compositional gradient and radial alignment of rod-shaped primary particles increasingly disappeared at calcination temperatures exceeding the optimal calcination temperature. FCG NCM78 calcined at the optimal calcination temperature retained the morphological texture of its precursor and demonstrated high crystallinity; the resulting cathode exhibited remarkable cycling stability, thereby retaining 86.3% of its initial capacity after 4000 cycles, and superior rate capability due to the availability of nearly straight diffusion paths for Li-ion transport across adjacent primary particles. In contrast, excessively coarsened FCG NCM78 cathode particles, which are obtained at high calcination temperatures, develop permanent microcracks during cycling, thereby facilitating severe structural damage of the cathode material by parasitic surface reactions and the rapid deterioration of the solid electrolyte interphase layer on the graphite anode surface due to the crossover of dissolved transition-metal ions. Therefore, for superior electrochemical performance, the physicochemical properties of FCG cathode materials should be carefully optimized by controlling the calcination process.

Particle morphology dependent dielectric properties of CaCu3Ti4O12/polyvinyl alcohol composite films

Flexible dielectrics with high dielectric constant and low loss have promising applications in many electronic devices. In this work, a binary composite with admirable dielectric properties was fabricated using a giant dielectric material CaCu3Ti4O12 (CCTO) as the filler and a non-ferroelectric and water-soluble polymer, polyvinyl alcohol (PVA) as the matrix. To optimize the dielectric properties, the effects of CCTO particle morphology on the dielectric properties of the CCTO/PVA composite films were detailed with the help of X-ray diffraction, scanning electron microscopy, and precision impedance analyzer. Compared with CCTO/PVA composite films filled with rod-shaped or irregular CCTO particles, composite films filled with square CCTO particles exhibited the highest dielectric constant and the maximum dielectric constant reached up to 45.5 while the dielectric loss was only 0.19 at 100 Hz. This work provides a promising way to fabricate PVA-based dielectric composites for practical applications in electronics.

Dynamics and instabilities of the free boundary of a two-dimensional dry active nematic aggregate

The dynamics of a two-dimensional aggregate of active rod-shaped particles in the nematic phase with a free boundary is considered theoretically. The aggregate is in contact with a hard boundary at y = 0, a free boundary at y = H(x, t), and in the x-direction the aggregate is of infinite extension. By assuming fast relaxation of the director field, we find instabilities driven by the coupling between the deformation of the free boundary and the active stress in parameter regimes where bulk systems are stable. For a contractile aggregate, when the particles are aligned parallel to the boundaries, the system is unstable in the long wavelengths at any strength of contractility for any H, and the critical wavelength increases as H increases; when the particles are aligned perpendicular to the boundaries, the system acquires a finite-wavelength instability at a critical active stress whose strength decreases as H increases. The behavior for an aggregate with steady-state particle density ρ s , strength of active stress χ, bulk modulus ρ s β, and particles aligned perpendicular to the boundaries can be mapped to one with active stress strength − χ, bulk modulus ρ s (β − χ), and particles aligned parallel to the boundaries. The stability of an extensile aggregate can be obtained from the analysis for contractile aggregates through this mapping as well, even though the corresponding physical mechanisms for the instabilities are different. In the limit H → ∞ , the free boundary is unstable for any contractile or extensile systems in the long-wavelength limit.

Synthesis and properties of ZnO on nonwoven PET fiber

Nano-ZnO was synthesized on PET fiber by two-step hydrothermal method. The morphology of the product is normalized, and it has good catalytic and antibacterial properties. • High-density ZnO was synthesized on PET fiber by a simple two-step hydrothermal method. • The ZnO@PET synthesized at 90 ℃ has the best morphology and crystallinity. • ZnO@PET exhibits the basic characteristics of ZnO, and has good photocatalytic and antibacterial properties. • Water washing caused the loss of ZnO, and the antibacterial property of 62% can be maintained after 20 washing cycles. A “seed” and “late growth” two-step chemical solution method was used to synthesize ZnO nanostructures on the surface of PET fiber (ZnO@PET). The products were processed by various methods. The results showed that ZnO synthesized on the fiber surface was composed of high-density rod-shaped particles, which had a hexagonal wurtzite structure. The FTIR result indicated that the product had characteristics of PET and ZnO. The UV–vis absorption spectrum showed a strong absorption in the ultraviolet band, and the PL result showed that the emission spectrum was a continuous spectrum centered at 395 nm. Materials with good morphology and crystallization above 60 °C could be synthesized. Under 254 nm ultraviolet light irradiation, ZnO@PET completely degraded the methyl orange standard solution within 700 min. The antibacterial property of ZnO@PET against Escherichia coli was 99%. After washing 20 times, the nano-ZnO was partially peeled off, but it maintained an antibacterial rate of 62%.

An alternating ageing-annealing process for enhancing strength and ductility of a Mg-Gd-Y-Zn-Zr alloy

In this paper, an alternating ageing-annealing process was proposed for an extruded Mg-9.5Gd-4Y-2.2Zn-0.5Zr (wt.%) alloy, and then the effects of this process on the microstructure, mechanical properties and fracture mechanism of the alloy were investigated. The results showed that short rod-shaped particles with long period stacking ordered (LPSO) phases and β′ phases were densely and uniformly distributed in the sample and exhibited a homogeneous microstructure after alternating ageing-annealing treatment, while after the traditional ageing treatment only basal γ′ phases were sparsely distributed in the fine grain region of the sample with a bimodal microstructure. Deformed grains with strong basal textures and deformation incompatibility between different regions (deformed grain region, fine grain region and bulk-shaped LPSO phase) were prone to high local stress concentrations, which caused the alloy to fracture without full work hardening. The sample possessed an excellent strength-ductility synergistic effect after alternating ageing-annealing treatment. This is mainly attributed to the coordinated deformation of the homogeneous microstructure and the pinning effect of the short rod-shaped LPSO phases and the prismatic β′ phases on dislocations and grain boundaries, which significantly improved the strength and inhibited the initiation of cracks. In summary, the mechanical properties of the sample were improved after heat treatment, with a yield strength (YS) of 425 MPa, an ultimate tensile strength (UTS) of 493.2 MPa, and an elongation (EL) of 11.2%.