Production of CNT-bearing melt-spun Al-2Sc-0.05CNT alloys

In the present work, rapidly solidified Ale2Sc-XCNT (X = 0, 0.05) alloys were successfully fabricated by melt spinning under Ar atmosphere. The effects of addition of CNT on the microstructural, thermal, microhardness, and electrical properties were investigated by using scanning electron microscopy (SEM), X-ray diffractometer (XRD), differential calorimeter (DSC), Vickers microhardness testing and a four point probe resistivity tester. Experimental results illustrated that the addition of 0.05 wt% CNT to melt-spun Al -2Sc alloys led to the formation of equiaxed globular-like morphologies with size from 0.3 to 2.7 mu m in. In the microstructure of Al-2Sc-0.05CNT alloy, CNTs covered by Al with size (width and length) changing from 40 to 55 nm and 255-295 nm, respectively, were observed. The addition of CNT led to a net increment (similar to 25%) in microhardness values due to solitary strengthening of the carbon nanotubes, solute solution hardening and modification of the morphologies of Al3Sc intermetallics. In addition, because of CNT addition there was a decrease in the electrical resistivity. (C) 2017 Elsevier B.V. All rights reserved

Formation of novel rice-like intermetallic phases and changes in the mechanical, microstructural and electrical properties of Sn-5Sb alloys with addition Ag and Bi

In the present study, the effects of Ag and Bi additions (1 wt.%) on the microstructural, thermal, mechanical and electrical properties of Sn-5Sb solder alloys were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), microhardness tests, and four probe measurements. It was observed that the melting point of Sn-5Sb solder alloy decreased with the addition of Ag and Bi. It was found that the final microstructure of rapidly solidified Sn-5Sb-1X (X = Ag and Bi) alloys was strictly dependent upon the wheel speeds; the microstructures changed from a coarse dendritic and needle-like structure to a refined ultra fine dendritic and rice-like structure with increasing wheel speed. Cooling rate was also effective on both the mechanical and electrical properties. It was found that all of the alloys exhibit higher mechanical properties with increasing cooling rate and/or decreasing testing temperature. Similarly, significant improvements of 32% and 9% in electrical conductivity of both of the alloys were obtained with the addition of Ag and Bi, respectively. The microstructural evolution of the Sn-5Sb based alloys plays a crucial role in influencing the mechanical properties of these alloys. (C) 2015 Elsevier B.V. All rights reserved

PRODUCTION OF MELT-SPUN Al-20Si-5Fe ALLOY AND BORON CARBIDE (B4C) COMPOSITE MATERIAL

In this study, metal matrix composite materials containing melt-spun Al-20Si-5Fe alloys and boron carbide was produced by high energy ball milling and then hot pressing at 200 MPa pressure and 450 degrees C. Mechanical and microstructural characterizations were performed by using an optical microscopy, X-Ray diffractometer, and dynamic microhardness tester. It was observed that boron carbide particles were homogenously distributed in the microstructure and values of microhardness and elastic modules were averagely 830 MPa and 42 GPa, respectively

Effect of Different Production Methods on the Mechanical and Microstructural Properties of Hypereutectic Al-Si Alloys

In this study, the effects of different production methods like melt spinning, high-energy ball milling, and combined melt spinning and high-energy ball milling on the mechanical and microstructural properties of hypereutectic Al-20Si-5Fe alloys were investigated. While microstructural and spectroscopic analyses were performed using scanning electron microscopy and X-ray diffractometry, mechanical properties were measured using a depth-sensing indentation instrument with a Berkovich tip. Microstructural and spectroscopic analyses demonstrate that high-energy ball milling process applied on the melt-spun Al-20-Si-5Fe alloy for 10 minutes brings about a reduction in the size of silicon particles and intermetallic compounds. However, further increase in milling time does not yield any significant reduction in size. High-energy ball milling for 10 minutes on the starting powders is not enough to form any intermetallic phase. According to the depth-sensing indentation experiments, high-energy milling of melt-spun Al-20Si-5Fe alloys shows an incremental behavior in terms of hardness values. For the Al-20Si-5Fe alloys investigated in this study, the production technique remarkably influences their elastic–plastic response to the indentation process in terms of both magnitude and shape of P-h curves. © 2014, The Minerals, Metals & Materials Society and ASM International.110M517The authors would like to thank the Scientific and Technological Research Council of Turkey (TÜBİTAK) for funding the project (Project number 110M517)

A new analytical model to estimate maximum internal socket depth of non-reduced strength bolts

In this study, an analytical model for calculation of the maximum socket depth of bolts having shaft diameter smaller than socket diameter was introduced. A representative bolt was chosen and maximum socket depth satisfying the minimum ultimate tensile strength was calculated by the developed analytical model. The analytical findings were also compared with numerical simulations for validation. Numerical studies were carried out by using Simufact.forming finite element software. The maximum socket depth estimated by using the developed analytical model was in good agreement with the numerical results. The obtained critical socket depth through the analytical model was 1.4% safer compared to numerical simulation results. Therefore, it was concluded that the developed analytical model could be used to estimate the critical socket depths of bolts having shaft diameter smaller than socket diameter. (C) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExC

Microstructure and microhardness of melt-spun Al-25Si-5Fe-XCo (X=0, 1, 3, 5) alloys

WOS: 000316536800003The microstructure and microhardness evolution of melt-spun Al-25Si-5Fe alloy with Co addition (1, 3 and 5 wt.%) were investigated. Microstructural and spectroscopic analyses demonstrate that Co could refine primary Si grains and change their morphology because it causes higher constitutional undercooling and has large mixing enthalpy with Si. Especially, 3 wt.% Co addition causes homogeneously distributed fine spherical Si particles in the rapidly solidified Al-25Si-5Fe alloy. The size of the spherical silicon particles was from around 200 to 600 nm near the wheel side region, and it varied from 800 nm to 1.3 mu m at the air side. The optimum ratio of Si and Co should be between 6 and 8.3 to form spherical Si grains in Al-25/30Si-5Fe alloys. A considerable improvement in microhardness value (from 211 to 370 HV) was obtained with the addition of Co. (C) 2013 Elsevier Inc. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [110M517]; Gaziosmanpasa University Department of Scientific Research Projects (BAP)Gaziosmanpasa University [2010/111]The authors would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK) for funding the project (project number 110M517). The authors would also like to thank the Gaziosmanpasa University Department of Scientific Research Projects (BAP) for funding the project (project number 2010/111)

Effect Of Sc Addition On The Microstructure And Mechanical Properties Of As-Atomized And Extruded Al-20Si Alloys

With the development of nanotechnologies, the number of industrial processes dealing with the production of nanostructures or nano-objects is in constant progress (microelectronics, metallurgy⋯). Thus, knowledge of atom mobility and the understanding of atom redistribution in nano-objects and during their fabrication have become subjects of increasing importance, since they are key parameters to control nano-fabrication. Especially, today\u27s materials can be both composed of nano-objects as clusters or decorated defects⋯, and contain a large number of interfaces as in nanometer-thick film stacking and buried nano-wires or nano-islands. Atom redistribution in this type of materials is quite complex due to the combination of different effects, such as composition and stress, and is still not very well known due to experimental issues. For example, it has been shown that atomic transport in nanocrystalline layers can be several orders of magnitude faster than in microcrystalline layers, though the reason for this mobility increase is still under debate. Effective diffusion in nanocrystalline layers is expected to be highly dependent on interface and grain boundary (GB) diffusion, as well as triple junction diffusion. However, experimental measurements of diffusion coefficients in nano-grains, nano-grain boundaries, triple junctions, and interfaces, as well as investigations concerning diffusion mechanisms, and defect formation and mobility in these different diffusion paths are today still needed, in order to give a complete picture of nano-diffusion and nano-size effects upon atom transport. In this paper, we present recent studies dealing with diffusion in nano-crystalline materials using original simulations combined with usual 1D composition profile measurements, or using the particular abilities of atom probe tomography (APT) to experimentally characterize interfaces. We present techniques allowing for the simultaneous measurement of grain and GB diffusion coefficients in polycrystals, as well as the measurement of nano-grain lattice diffusion and triple junction diffusion. We also show that laserassisted APT microscopy is the ideal tool to study interface diffusion and nano-diffusion in nanostructures, since it allows the determination of 1D, 2D and 3D atomic distributions that can be analyzed using diffusion analytical solutions or numerical simulation. © 2012 Trans Tech Publications, Switzerland

Effect of heat treatment on magnetic properties of nanocomposite Nd-lean Nd7Fe73B20 ribbons

In this work, we explored the effect of heat treatment on high boron and Nd-lean content magnetic Nd7Fe73B20 nanocomposite materials via vibration sample magnetometer (VSM), X-ray diffraction, differential thermal analysis (DTA), and scanning electron microscope (SEM). The Scherer formula was employed to estimate the effect in the crystal size of the heat treatment on high boron and Nd-lean content magnetic Nd7Fe73B20 nanocomposite materials. We heat-treated samples in different conditions to obtain optimum magnetic properties. Our high-throughput fabrication strategy allows us to elucidate the possibility of obtaining Nd-lean nanocomposite NdFeB magnet in terms of the melt-spinning. We evaluated the influence of heat treatment on the Nd-lean NdFeB/alpha-Fe nanocomposite magnets produced by melt-spinning. Here, in the heat-treated ribbon at 750 degrees C for 30 min, we obtained a combination of coercivity of 450 Oe, a high-saturation magnetization of 232 emu/g in the heat-treated ribbon at 650 degrees C for 30 min, which surpasses most traditional nanocrystalline magnets based on Fe-Co and pricey. The results we present here are expected to serve as a guideline for designing new magnets for industrial applications