This study confirms that crystalline TiB2 particles can act as a potent site for the heterogeneous nucleation of the metastable icosahedral quasicrystalline phase (IQC) formed in cast Al-Mn-Si-Cu-Mg ...alloys. The results show that a primary metastable IQC phase nucleates on facets of TiB2 particles. Electron backscatter diffraction patterns and selected-area electron diffraction patterns confirmed that at least five orientation relationships (ORs) exist between the stable TiB2 and the metastable IQC phase. The IQC adopts different ORs with the crystallineTiB2 particles to form low energy interfaces by matching close-packed planes at the interfaces. In the IQC phase, the close-packed planes are the 5-fold and 2-fold. Microstructural analyses show that inoculation has a noticeable influence on the size and distribution of the primary IQC phase, which in turn has a noticeable influence on the compressive properties of the investigated alloys. Due to their exceptional mechanical properties, these alloys could become a prime candidate for lightweight applications, especially in the automotive and aerospace industries.
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•This work confirms for the first time that crystalline TiB2 inoculants can serve as an effective substrate for IQC phase nucleation.•EBSD and SAED patterns confirm that at least five orientation relationships exist between the close-packed planes of the phases.•The microstructural analyses show that inoculation has a noticeable effect on the size and distribution of the primary IQC phase.•The size and distribution of the primary IQC phase clearly affect the compressive properties.•As-cast, a compressive yield strength of 380 MPa, a compressive strength of 680 MPa, and a compressive fracture strain of 20 % were achieved.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Polylactic acid (PLA) is one of the most suitable materials for 3D printing. Blending with nanoparticles improves some of its properties, broadening its application possibilities. The article ...presents a study of composite PLA matrix filaments with added unmodified and lignin/polymerised lignin surface-modified nanofibrillated cellulose (NFC). The influence of untreated and surface-modified NFC on morphological, mechanical, technological, infrared spectroscopic, and dynamic mechanical properties was evaluated for different groups of samples. As determined by the stereo and scanning electron microscopy, the unmodified and surface-modified NFCs with lignin and polymerised lignin were present in the form of plate-shaped agglomerates. The addition of NFC slightly reduced the filaments' tensile strength, stretchability, and ability to absorb energy, while in contrast, the initial modulus slightly improved. By adding NFC to the PLA matrix, the bending storage modulus (E') decreased slightly at lower temperatures, especially in the PLA samples with 3 wt% and 5 wt% NFC. When NFC was modified with lignin and polymerised lignin, an increase in E' was noticed, especially in the glassy state.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This work deals with the influence of gallium addition on the constitution and formation of the phases in the Al-rich corner of the Al–Mn system during casting. Al-rich binary Al–Mn and ternary ...Al–Mn–Ga alloys were cast into a copper mould with a cavity diameter of 5 mm. The microstructures of the produced alloys were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction and X-ray diffraction. The characterization revealed the presence of αAl, Al6Mn, λ-Al4Mn, L-Al4Mn, icosahedral quasicrystals (IQCs) and decagonal quasicrystals (DQCs). As the amount of gallium in the synthesized alloys increased, the proportion of the phases varied and IQCs and DQCs were formed. Microanalysis revealed that IQCs contained more gallium and less manganese than DQCs.
•Binary Al–Mn and ternary Al–Mn–Ga alloys were cast in a copper mould and characterized by SEM, EDS, EBSD and XRD.•Characterization of the alloys shows that αAl, Al6Mn, λ-Al4Mn, L-Al4Mn, IQCs and DQCs are present.•The EDS microanalysis shows that more gallium is present in the IQCs than in the DQCs.•The results reveal that with the addition of gallium to the binary Al–Mn system, L-Al4Mn, IQCs and in some cases DQCs form.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This investigation deals with the influence of calcium, strontium and zinc on the formation of primary, metastable quasicrystals in Al-Mn-Si alloys as these can enhance the mechanical properties of ...alloys. The synthesized alloys were cast into a copper mould. The castings were characterized using standard tools for studying microstructure. The Al-Mn-Si-Zn-Ca-Sr alloy contained more of the primary icosahedral quasicrystalline (iQc) phase and less of the approximant α-Al-Mn-Si phase than the Al-Mn-Si alloy. The higher volume fraction of the primary iQc phase in the Al-Mn-Si-Zn-Ca-Sr alloy is explained by the reduction of the critical radius size for nucleation and by an increase in the number of nucleation sites for the iQc phase. Increased number of nucleation sites and higher volume fraction of the primary iQc are both related to a reduction of the surface tension for the Al-based melt caused by the presence of calcium and strontium. These two elements do not become incorporated into the iQc phase but have a large effect on the course of the solidification of the investigated alloys and their constitution at room temperature.
We prepared three Al–Mn-based alloys with different copper, magnesium and silicon contents by casting into cylindrical copper molds. All the alloys exhibited primary metastable quasicrystals (QCs). ...In order to confirm the presence of either primary decagonal QCs (dQCs) or icosahedral QCs (iQCs) and to determine their compositions, the castings were characterized by means of light microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), electron-backscatter diffraction and X-ray diffraction. The dQCs are present in the Al–Mn-based alloys containing copper. In the case of the combined presence of copper and magnesium, iQCs are present in the edge region and dQCs are present in the central region. In the alloy containing copper, magnesium and silicon, iQCs are present in the casting. The average metallic radius (AMR) and electron-to-atom ratio of these primary phases were calculated by taking into account the composition of these primary phases, as determined by EDS. The AMR shows different values in the cases of dQCs and iQCs. Equal mean values of the AMR were found in iQCs with markedly different compositions. Furthermore, all the metastable QCs in this work show electron concentrations close to 2.6.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study confirms that the stable icosahedral quasicrystal (iQc) phase Al65Cu20Fe15 (iQc–AlCuFe) can serve as a substrate for the nucleation of the metastable iQc–AlMnSi phase formed in rapidly ...solidified Al–Mn–Si alloys. The results reveal that a continuous, thin layer of the metastable iQc–AlMnSi phase can be formed on a stable iQc–AlCuFe particle. Electron backscatter diffraction patterns and selected-area electron diffraction patterns confirmed that epitaxy exists between the stable and the metastable iQc phases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This paper deals with the characterization of three different commercial, WC-Co cemented-carbide tools in the form of saw blades, one group of which exhibits more frequent cracking. Since the ...properties of these materials largely depend on the microstructure, a detailed characterization was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The SEM image analysis included a determination of the binder content and the mean WC grain area. The average chemical composition of these materials was also determined using an X-ray fluorescence (XRF) analyser. The results show that despite the same content of binder-forming elements in all three WC-Co cemented-carbide materials, the material that cracked more frequently contained a smaller amount of binder and a lower mean WC grain area, both of which are known to reduce the toughness of such a material.
An Al–Mn alloy with additions of copper, magnesium, and silicon was prepared and cast into a copper mold. It contains in situ-formed icosahedral quasicrystals (iQCs), as confirmed by electron ...backscatter diffraction. The aim of this work is to present the mechanical and corrosion properties of this alloy and compare its properties with some conventional commercial materials. The compressive strength and compressive yield strength were 751 MPa and 377 MPa, while the compressive fracture strain was 19%. It was observed that intensive shearing caused the final fracture of the specimens and the fractured iQC dendrites still showed cohesion with the α-Al matrix. The polarization resistance and corrosion rate of the artificially aged alloy were 7.30 kΩ and 1.2 μm/year. The evaluated properties are comparable to conventional, discontinuously reinforced aluminum metal-matrix composites and structural wrought aluminum alloys.
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