Volume Fraction Of Crystalline Phase Research Articles

Unveiling the effect of Nb and Zr additions on microstructure and properties of β Ti-25Ta alloys for biomedical applications

This study aims to analyze the influence of niobium and zirconium in the structure, microstructure, and mechanical properties of quaternary Ti-25Ta-Zr-Nb alloys system: Ti-25Ta, Ti-25Ta-10Zr-15Nb, and Ti-25Ta-20Zr-30Nb (wt%). The structural and microstructural analyses were performed using X-ray diffraction, as well as optical, scanning and transmission electron microscopy. Rietveld method was used for calculating the volume fractions of crystalline phases and values of β lattice parameters. Williamson-Hall's equation calculated the micro-strain and average size of the β-phase crystallite. The mechanical properties were analyzed by microhardness and Young's modulus measurements. The results show that the different heat treatments influence the structure of the materials and the mechanical properties: Rapid cooling treatments induced the formation of α″ and β for Ti-25Ta-10Zr-15Nb (TTZN1), while the treatments with slow cooling induced the formation of α phases. The Ti-25Ta-20Zr-30Nb (TTZN2) alloy is a stable β, so heat treatments could not change the crystalline structure. To Ti-25Ta alloy, in all study conditions, the alloy has α + α″ phases. Regarding the lattice parameters, adding niobium to the alloys increased the lattice parameter of the β phase. Concerning the β phase micro-strain and average crystal size, the heat treatments increased the average size and micro-strain due to the crystallization of the crystals. β-Ti alloys in the solubilized heat treatment condition, followed by rapid cooling, showed better mechanical biocompatibility results due to the low elastic modulus, highlighting the metastable β Ti-25Ta-10Zr-15Nb alloy, which showed a low elastic modulus of 50 GPa.

Synthesis and Characterization of a Novel Nanocomposite Polymer

One-dimensional nanostructures of PANI: PVA-g-EI nanocomposite are prepared by the interfacial polymerization method. The properties of a resulting green powder are studied by the X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), and infrared spectroscopy (FTIR). Prepared thin films were characterized by UV-Vis and photoluminescence (PL) spectroscopies. The XRD pattern of the nanocomposite shows that the higher volume fraction of crystalline phases corresponds to the PANI polymer with the accepted monoclinic unit cell of PVA. Nano-sized irregular particles arranged in clusters appear in the TEM measurements and SEM images, which testifies to the agglomeration without uniform packing. EDX confirms that the PVA-g-EI is incorporated in the structure of the polymer nanocomposite. A significant shift in the absorption edge with three PL independent emission peaks again confirms that PANI/PVA-g-EI form a nanocomposite.

Reactive metal additive manufacturing: Surface near ZrN–metallic glass composite formation and mechanical properties

ZrN formation in a Zr-based bulk metallic glass is observed after processing using reactive laser powder bed fusion. Two processing routes employing nitrogen as a reactive process gas are explored: (1) Standard inert processing in argon followed by reactive remelting in nitrogen and (2) reactive processing in nitrogen. Incorporation of nitrogen is depth-dependent and both approaches result in a dispersion of ZrN nanocrystals in the amorphous matrix close to the surface. The process parameters can be adjusted to control the volume fraction of crystalline phases formed. Hence, it is shown that reactive additive manufacturing can be utilised to form bulk metallic glass–ceramic composites in surface near regions. Thereby we demonstrate that the reactive gas atmosphere utilised during additive manufacturing enables local tailoring of structure, composition, and mechanical properties in the vicinity of the surface.

Enhanced corrosion resistance of a ZrCuNiAl bulk metallic glass in simulated groundwater by minor crystallization

Understanding the corrosion behaviors of bulk metallic glasses (BMGs) in practical working environment is essential for the applications of BMGs as corrosion resistance materials. The present work investigated the corrosion behaviors of Zr50.7Cu28Ni9Al12.3 (at. %) BMG and also its heat treated alloys with different volume fraction of crystalline phase in a solution simulating groundwater. It was shown that the corrosion of the present ZrCuNiAl alloy is induced by pit etching and Cu would be aggregated at the corrosion positions in a form of Cu2+ ions. Zr, Ni and Al would inversely be dissolved by the simulated groundwater and so were lack at the corrosion positions, and they are probed as form of Zr4+, Ni2+ and Al3+ ions on the corrosion surface, which supports the formation of metal oxides ZrO2, CuO, NiO and Al2O3. The experimental results discover a corrosion resistance trend first enhancing and then reducing with increasing crystalline phase volume fraction, proving that minor crystallization in fact also improve corrosion resistance in this BMG system, but large volume fraction of crystalline phases would deteriorate the anti-corrosion performance of BMGs. Thus the amorphous state itself improves corrosion resistance of the studied alloy.

Effect of type and volume fraction of crystallization products on the variations of electrical resistivity in Cu47Ti34Zr11Ni8 and Ti40Zr25Cu12Ni3Be20 metallic glasses

The variation of electrical resistivity can be an indicative of the crystallization path for metallic glass (MG). The primary phases of Cu47Ti34Zr11Ni8 and Ti40Zr25Cu12Ni3Be20 MGs are Cu3Ti and quasicrystal, respectively, which further influences change of electrical resistivity at the onset crystallization temperature (Tx1). The former shows a rapidly drop in the electrical resistivity curve along with apparent change in curve slope at Tx1, while the latter exhibits a long and continuous decrement of electrical resistivity from Tg to Tx2 without obvious change of curve slope at Tx1. The nanoscale quasicrystal with slower growth rate indicates that the icosahedral short-range orders might exist during sample preparation, which could easily overcome crystallization obstacle and transform into the quasicrystalline phase continuously, inducing the special change of the Ti40Zr25Cu12Ni3Be20 MG. Meanwhile, the TCR of the crystalline/glass composite materials depends on the volume fraction of crystalline phase. When the volume fraction of crystalline phases is small, the TCR is still determined by the residual amorphous phase.

Crystallization, thermal expansion and hardness of Y2O3–Al2O3–SiO2 glasses

The effect of crystallization of y-Y2Si2O7 (Y-c and Y2S-c2)/Y4.67(SiO4)3O (Y2S-c1) single crystal or simultaneously y-Y2Si2O7, Al6Si2O13 and SiO2 crystals (YMS-c) on the hardness and thermal expansion coefficient (TEC) of Y2O3–Al2O3–SiO2 (YAS) glass is studied. Crystallization activation energy is 591, 650 and 282 kJ/mol for Y, Y2S and YMS glasses, crystallization mechanisms of glasses Y and Y2S (Tc1) are surface crystallization and one-dimensional crystal growth, while YMS glass is two- and one-dimensional growth of crystals. The volume fraction of crystalline phases in Y-c (91.45%), Y2S-c1 (83.00%) and -c2 (92.55%) glass ceramics are larger than that of YMS-c (71.11%), precipitated y-Y2Si2O7 single crystal decrease the TEC ( × 10−6 °C−1/30–1000 °C) of Y and Y2S parent glasses to 3.95 (Y-c) and 5.09 (Y2S-c2) while Y4.67(SiO4)3O single crystal increase the TEC of Y2S-c1 to 7.15, YMS-c has the smallest TEC (3.34) among studied glass ceramics, the enhancing effect of Y4.67(SiO4)3O on the hardness of Y2S glass is more than that of y-Y2Si2O7. Y and YMS glasses could be used as coating, sealing and jointing materials for SiC ceramics used in the high temperature fields.

Influence of Reinforcement Oxides on Structural and Mechanical Properties of Glass-Ceramics: A Review Article

This review studied the mechanical behaviors of Glass ceramics (GC) based on the Al2O3/SiO2 system. Glass ceramics are great interest due to their wide variety of applications, which have the ability to fulfil the recent demands of advanced mechanical, optical and biomedical applications. Glass-ceramics are typically heat-stable and have greater mechanical features than glasses. In addition, mechanical properties can be customized to provide variable volume fractions of crystalline phases by regulating nucleation and growth of the crystalline phases. The distribution of these crystalline phases in the glass matrix increases the consistency of the material and, in comparison, effectively limits the growth of cracks. The crystallization process resulted in substantial improvements in micro-hardness and density values such as sodium calcium phosphate (Na4Ca(PO3)6 and calcium pyrophosphate (β-Ca2P2O7) had sufficient properties for bone grafts and dental applications. This article outlines recent developments in the field of doping Oxides as reinforced with SiO2-Al2O3-based Glass- ceramics, to enhance the mechanical properties of Glass-ceramics combination. The research focused on the mechanical and the tribological behaviour of Biomedical, Electronics applications and selection of fabrication methods.

Structure Types of Kidney Stones and Their Susceptibility to Shock Wave Fragmentation.

Background:The modern approach in the treatment of urolithiasis involves the use of non-invasive and minimally invasive techniques based on the stone fragmentation, among which shock wave lithotripsy (SWL) is considered as the first-line treatment for kidney stones < 2 cm and proximal ureter stones.Objective:To study the microstructure and mineral composition of kidney stones and to evaluate their influence on the stones’ susceptibility to fragmentation by shock waves.Methods:The microstructure and mineral composition of kidney stone samples obtained from shock wave lithotripsy in 87 patients were studied using crystal optical analysis and infrared spectroscopy. The volume fraction of amorphous and crystalline phases of the stone composition, the quantitative and qualitative composition of mineral components were assessed. The fragmentation features of stones with different microstructure were retrospectively analyzed based on the total number of shock waves required for complete stone fragmentation.Results:Three kidney stone structure types were identified: amorphous-crystalline structure stones predominantly including the amorphous phase (type A); amorphous-crystalline structure stones predominantly including the crystalline phase (type B); fully crystalline structure stones (type C). Significant positive correlation between the total number of shock waves required for complete stone fragmentation and the volume fraction of crystalline phase was found.Conclusion:The structure type of kidney stones is determined by the volume ratio between the amorphous and crystalline phases of their composition. The amorphous-crystalline structure stones with the predominant content of the amorphous phase are more sensitive to shock-wave exposure. The increase in the volume fraction of crystalline phase in the stone structure reduces the stone’s susceptibility to fragmentation by shock waves.

Effects of microstructures on the mechanical properties of lithium disilicate glass-ceramics for the SiO2–Li2O–P2O5–K2O–ZnO system

The effects of microstructures on the mechanical properties of lithium disilicate (Li 2 Si 2 O 5 :LS2) glass-ceramics (GCs) were carefully investigated for the SiO 2 –Li 2 O–P 2 O 5 –K 2 O–ZnO system. The microstructures of GC samples, having three different compositions but the same total 6 mol% of additives (P 2 O 5 , ZnO, K 2 O), could be controlled by varying heat treatment conditions of glass samples. In addition to major LS2 crystalline phase, two other minor crystalline phases of Li 3 PO 4 (LP) and cristobalite were detectable. Average crystal sizes of GC samples were in the region of 0.3–10 μm, and the volume fractions of crystalline phases were in the region of 0.70–0.73. The biaxial flexural strength was improved with decreasing the average crystal size from ~10 to ~1 μm by following the Hall-Petch relation, and the maximum flexural strength of 445.8 ± 7.2 MPa was obtainable from the GC samples with the additive compositions of 1.5 mol% P 2 O 5 , 2.75 mol% K 2 O and 2 mol% of ZnO which were nucleated at 540 °C for 1 h and grown at 850 °C for 4 h. When 8.4 vol% cristobalite was incorporated into the sample, however, there was a severe scattering in flexural strength data due to the formation of microcracks induced by the beta-to-alpha transition of cristobalite and also due to a micro tensile stress in the residual glassy phase induced by a large difference in thermal expansion coefficients between crystal and residual glassy phases. Meanwhile, the Vickers hardness was increased with decreasing the average crystal size down to ~0.3 μm, indicating that the factors for the deterioration of flexural strength have a negligible effect on hardness.

The impact of different volume fractions of crystalline structures on the electrochemical behaviour of Mg67Zn29Ca4 alloys for biomedical applications

ABSTRACTIn this work, the influence of various volume fractions of the crystalline phase in an amorphous matrix of Mg67Zn29Ca4 alloys was investigated for its corrosion resistance for biodegradable applications. An amorphous Mg67Zn29Ca4 alloy was successfully fabricated using melt casting into a copper mould. Then, to obtain different ratios of the crystalline phase in an amorphous matrix, the obtained amorphous rods with 3 mm diameters were annealed at 190, 230, 250, and 400°C. The volume fraction of the crystalline phase was measured by X-ray diffraction, and the microstructures of the obtained alloys were determined based on scanning electron microscopy images. Electrochemical testing was conducted in simulated body fluid at 37°C. This report shows that the ratio of the volume fractions of amorphous and crystalline phases in alloy microstructures strongly influences their corrosion behaviours. The alloy with a fully amorphous structure was the most resistive in the analysed media.

In situ study of the shear band features of a CuZr-based bulk metallic glass composite

To understand the shear banding evolution and the effect of individual shear band on deformation mechanisms of bulk metallic glass composites (BMGCs), tensile tests of CuZrAlNb BMGCs have been in situ studied. It is found that the type and sequence of shear bands are independent of volume fraction of crystalline phase. All the types of shear bands can be considered as shear bands controlled by stress affected zones (SAZs) at crystal/matrix interface and those far away from SAZs. Based on the analysis of elastic energy dissipation, the shear bands far away from SAZs play a dominant role in the deformation stability. For current BMGCs, the propagation of shear bands far away from SAZs can be delayed by reducing the average elastic energy dissipation. High Young's modulus and volume fraction of crystalline phase are effective for decreasing the average elastic energy stored in shear bands. It is expected that the obtained results can offer better understanding of deformation mechanism in bulk metallic glass composites, which should be beneficial to design bulk metallic glass composites with improved mechanical performances.

Giant enhancement of free charge carrier concentration in boron-doped amorphous hydrogenated silicon under femtosecond laser crystallization

The modification of boron-doped amorphous hydrogenated silicon films [a-Si:H(B)] with femtosecond laser radiation is studied in this work. It is demonstrated that femtosecond laser crystallization of the a-Si:H(B) film area leads to extremely high values of the free charge carrier (hole) concentration, which is typical for degenerated semiconductors. The free charge carrier concentration is locally determined by measuring the Raman spectra in the modified areas. The shape of Raman spectra is typical for Fano resonance. It is found that the charge carrier concentration in the modified areas may exceed 1020 cm−3 depending on the femtosecond irradiation conditions. The areas with such a high concentration of free charge carriers are also characterized by high volume fraction of crystalline phase (more than 90%). Such a sharp increase in the free charge carrier concentration in the modified areas may be explained by an increase in concentration of electrically active boron atoms. The activation energy of the temperature dependence of the conductivity for laser beam treated areas is in full agreement with the data obtained from the analysis of the Raman scattering spectra.

Effect of Cu Presence on Evolution of Mechanical and Magnetic Properties in a Novel Fe-Based Bulk Metallic Glass During Partial Annealing Process

Fe-based bulk metallic glasses (BMGs) often demonstrate extremely poor toughness at room temperature, which seriously limit their widespread application. This study is focused on the improvement of mechanical properties (especially toughness) and ferromagnetic manner of a new Fe-based BMG by using partial annealing and minor addition of Cu as an alloying element simultaneously. The results revealed that the volume fraction of crystalline phases increased with the minor addition of Cu during the partial annealing process. Therefore, maximum hardness and toughness were observed in the alloy with 0.25 at. pct Cu after annealing within a temperature range of the fourth crystallization stage due to the high Poisson’s ratios (υ) of this element and the presence of nano-crystalline phases in the amorphous matrix with an optimal average size. Also, saturation magnetization of the as-cast BMG increased with the minor addition of Cu due to the formation of short-range order regions. While with addition of Cu, this magnetic parameter was reduced in annealed alloys due to an increase in the concentration of non-magnetic Cu atoms around the α-Fe nano-crystals.

Investigation of fluctuation behavior in viscosity of coal slags used in entrained-flow gasifiers

Entrained-flow gasification has attracted extensive attention because of its clean and efficient utilization of coal as well as flexible application in industry for power generation and chemical production. Numerous theoretical and experimental investigations on slag flow in entrained-flow gasifiers have been performed to ensure a smooth operation, but an unscheduled shutdown due to slag tap blockage remains an ongoing challenge. A fluctuation phenomenon of slag viscosity gives a rise in the risk of slag tap blockage. In this work, three Chinese coal slags with low silicon content and high iron content were used to investigate the viscosity fluctuation phenomenon. It was found that the crystalline phases and suspended bubbles can cause the fluctuation phenomenon. The fluctuation degree is related to the volume fraction of crystalline phases and the crystallization rate. In the search for the mechanism of the viscosity fluctuation, an in-situ observation using a high temperature stage microscope system (HTSM) in combination with XRD and SEM analyses was carried out. In addition, the viscosity of investigated slags with the suppression of solid phases as well as the phase distribution at high temperatures was calculated. Based on a comprehensive analysis of the results, a possible mechanism has been proposed that the viscosity fluctuation is attributed to an instant local change in the macrostructure such as the deformation of suspended bubbles, the change of the orientation of acicular crystals and the interaction of the acicular crystals and suspended bubbles.

Microstructural and phase evolutions: Their dependent mechanical and magnetic properties in a Fe-based amorphous alloy during annealing process

In this study, the microstructural and phase evolutions of Fe41Co7Cr15Mo14Y2C15B6 amorphous alloy were investigated during annealing process to enhance the its mechanical and magnetic properties. The results showed that the crystalline phases including Fe23(B,C)6, Mo3Fe3C, and Mo3Co3C were formed during the annealing process, so that the volume fraction of these phases increased up to 32.3% by annealing at 928 °C. The mechanical behavior of investigated bulk metallic glass (BMG) was investigated by means of indentation testing. The cracking system types consist in Palmqvist cracks were obtained by means of stepwise polishing. Hardness and indentation toughness increased by an increase in crystallization temperature, simultaneously. Also, the ferromagnetic properties were significantly improved by increasing the volume fraction of crystalline phases.

Preparation and characterization of blend polymer electrolyte film based on poly(vinyl alcohol)-poly(acrylonitrile)/MgCl2 for energy storage devices

The development of magnesium electrolytes for battery applications has been the demand for electrochemical devices. To meet such demand, in this work solid blend polymer electrolytes were prepared using polyvinyl alcohol (PVA) and polyacrylonitrile (PAN) (92.5PVA:7.5PAN) as host polymer, magnesium chloride (MgCl2) of different molar mass percentage (m.m.%) (0.1, 0.2, 0.3, 0.4, 0.5, and 0.6%) as salt and dimethylformamide (DMF) as solvent. Structural, vibrational, thermal, electrical, and electrochemical properties of the prepared electrolytes were investigated using different techniques such as X-ray diffraction pattern, FTIR spectroscopy analysis, differential scanning calorimetry (DSC), AC impedance measurement, and transference number measurement. X-ray diffraction studies confirm the minimum volume fraction of crystalline phase for the polymer electrolyte with 0.5 m.m.% of MgCl2. FTIR confirms the complex formation between host polymer and salt. DSC analysis proves the thermal transition of the prepared films are affected by salt concentration. The optimized material with 0.5 m.m.% of MgCl2 offers a maximum electrical conductivity of 1.01 × 10−3 S cm−1 at room temperature. The Mg2+ ion conduction in the blend polymer electrolyte is confirmed from transference number measurement. Electrochemical analysis demonstrates the promising characteristic of these polymer films suitable as electrolytes for primary magnesium batteries. Output potential and discharge characteristics have been analyzed for primary magnesium battery which is constructed using optimized conducting electrolyte.

Effect of ion irradiation on the nanocrystallization and magnetic properties of soft magnetic Fe72.5Cu1Nb2Mo1.5Si14B9 alloy

The effect of accelerated Ar+ ions on the crystallization process and magnetic properties of nanocrystalline Fe72.5Cu1Nb2Mo1.5Si14B9 alloy has been studied using X-ray diffraction analysis, transmission electron microscopy, thermomagnetic analysis, and other magnetic methods. Irradiation by Ar+ ions with an energy of 30 keV and a fluence of 3.75 × 1015 cm–2 at short-term heating to a temperature of 620 K (which is 150 K below the thermal threshold of crystallization) leads to the complete crystallization of amorphous alloy, which is accompanied by the precipitation of the α-Fe(Si) solid solution crystals (close in composition to Fe80Si20), Fe3Si stable phase, and metastable hexagonal phases. The crystallization caused by irradiation leads to an increase in the grain size and changes the morphology of grain boundaries and volume fraction of crystalline phases, which is accompanied by changes in the magnetic properties.

Preparation and investigation of Ga5[GeSx]85I10 glasses

The Ga5[GeSx]85I10 glasses with x=1.5, 1.7, 2.0, 2.3 and 2.6 are prepared; their thermal and optical properties and stability against crystallization are investigated. The values of glass transition temperature, energy bandgap and volume fraction of crystalline phase in glasses after annealing have nonmonotonic dependence on the macro-composition with a maximum value at x=2.0. In the DSC curves of glasses with x=2.0, 2.3 and 2.6, two glass transition temperatures are registered. The glass samples containing 1.2ppm(at) hydrogen impurity in the form of SH-group and <1ppm(at) oxygen impurity in the form of GeO were produced.

Designing ductile CuZr-based metallic glass matrix composites

The CuZr-based metallic glass matrix composites (MGMCs) with different volume fractions of crystalline phases were designed by doping of nickel. Minor addition of nickel element can change the glass-forming ability of the resultant composites. Large compressive plasticity accompanied by strong work-hardening capacity was achieved in the Cu47Zr48Al4Ni1 composite with a volume fraction of crystalline phases of 33%. The excellent compressive properties were mainly attributed to the inhibition for the propagation of shear bands by the ductile crystals and deformation induced martensitic transformation of the B2-CuZr phase. However, no obvious global tensile ductility was obtained, due to the mode I fracture toughness and small plastic-zone size of glass matrix. To uncover the shear-band evolution during deformation, finite element simulation was conducted, revealing that the ductile B2 phase can tune the shear-stress distribution and consequently initiate and retard shear bands, which stimulates the multiplication of shear bands. Accordingly, the spacing of B2 CuZr particles is a vital factor dominating the plasticity of CuZr-based MGMCs, especially upon tension.

Phase formation and mechanical properties of Cu-Zr-Ti bulk metallic glass composites

The effect of the type of the crystalline phase and its volume fraction on the mechanical property of Cu50Zr50-xTix alloys (x = 0-10) bulk metallic glass composites has been investigated in this study. Up to 6 at% of Ti, B19’ phase particles distributed in the glassy matrix, while at 8 and 10% of Ti, B2 phase particles are retained in the glass matrix due to suppression of the eutectoid transformation of B2 phase and by avoidance of martensitic transformation of B2 into B19’. The volume fraction of crystalline phase is strongly dependent on the cooling rate. The larger volume fraction of the crystalline phases results in the lower yield stress, the higher plastic strain, and the more pronounced work hardening behavior. At the crystalline volume fraction below ~30%, the variation of the yield strength can be described by the rule of mixture model (ROM), while at the crystalline volume fraction higher than ~50% by the load-bearing model (LBM). At the crystal fractions between 30 and 50%, there is a yield strength drop and a transition from the ROM to the LBM. This transition is due to the formation of the crystalline structural framework at higher crystal fraction.