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    Influence of Ti, B and Sr on the microstructure and mechanical properties of A356 alloy
    (2011) Mallapur, D.G.; Kori, S.A.; Udupa, K.R.
    In the present investigation, the microstructural and mechanical properties study of A356 alloy have been discussed. The microstructural aspect of cast A356 alloy employed in the present study is strongly dependent on the grain refinement (Ti and B) and modification (Sr). The mechanical properties such as PS, UTS, %E, %R, YM and VHN have been investigated. This paper deals with the combined effect of grain refinement and modification, which improves the overall mechanical properties of the alloy. It is also a well-known fact that the mechanical properties of cast A356 alloy were improved by subjecting suitable melt treatment such as grain refinement, modification and mould vibration, etc. The quality of castings and their properties can be achieved by refining of ?-Al dendrites in A356 alloy by means of the addition of elements such as Ti and B which reduces the size of a-Al dendrites, which otherwise solidifies with coarse columnar a-Al dendritic structure. In addition, modification is normally adopted to achieve improved mechanical properties. Metallographic studies reveal that the structure changes from coarse columnar dendrites to fine equiaxed ones on the addition of grain refiner and further, plate like eutectic silicon to fine particles on addition of 0.20% of Al-10Sr modifier. The present result shows that a reduction in the size of a-Al dendrites, modification of eutectic Si and improvement in the mechanical properties were observed with the addition of grain refiner Al-3Ti, Al-3B and modifier Al-10Sr either individual addition or in combination. The change in the microstructure from coarse columnar ?-Al dendrites to fine equiaxed dendrites and plate like eutectic silicon to rounded particles leads to improved mechanical properties. © Springer Science+Business Media, LLC 2010.
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    Impact of ECAP on wear performance of Al-Mn magnesium alloy
    (Institute of Physics Publishing helen.craven@iop.org, 2020) Gopi, K.R.; Shivananda, N.H.
    The current study examines the wear performance of deformed AM90 magnesium alloy using pin-on-disc wear test apparatus under varying load of 30 and 40 N with the sliding distance of 2500 m and 5000 m at constant sliding speed of 3 m s-1. The samples were processed through equal channel angular pressing were subjected to microstructural, wear studies and are characterized by optical and scanning electron microscopy. Vickers microhardness was carried out to evaluate the relation between the wear behavior of homogenized and ECAP processed samples. Increment in number of ECAP passes increased the grain refinement as observed in the microstructure with reduction in grain size from ?70 ?m (homogenized sample) to ?4 ?m (ECAP 4 pass sample). Increase in wear resistance and hardness were observed for processed samples and the worn faces are analyzed by scanning electron microscopy and energy-dispersive X-ray spectrometer. The worn surfaces revealed the occurrence of wear debris, delamination, ploughing in the direction of sliding and the predominant wear mechanism was considered to be the combination of oxidation and abrasive wear. © 2020 The Author(s). Published by IOP Publishing Ltd.
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    Microstructural and mechanical properties of AlCoCrCuFeNiSix (x = 0 and 0.9) high entropy alloys
    (Elsevier Ltd, 2021) Chandrakar, R.; Kumar, A.; Chandraker, S.; Rao, K.R.; Chopkar, M.
    In this work, the effect of addition of Si on the phase evolution and mechanical properties of AlCoCrCuFeNiSix alloy system has been studied. The High Entropy Alloys (x = 0 and 0.9) have been synthesised by powder metallurgy route which includes mechanical alloying (MA) and spark plasma sintering. X-ray diffraction technique was performed to understand the alloying behaviour and to investigate the phase formation of the high entropy alloys. The samples after spark plasma sintering comprised mainly of body centered cubic structured phase with a small extent of face centered cubic structured phase. With the addition of silicon, the XRD peak intensity of body centered cubic appears strong compared to the face centered cubic structured phase. Moreover, no intermetallic is observed in AlCoCrCuFeNi high entropy alloy system. However, further accumulation of Silicon results in the evolution of sigma (?) phase. © 2020 Elsevier Ltd
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    EFFECT of LASER POST-TREATMENT on MICROSTRUCTURAL and SLIDING WEAR BEHAVIOR of HVOF-SPRAYED NiCrC and NiCrSi COATINGS
    (World Scientific, 2022) Naik, T.; Mathapati, M.; Prasad, C.D.; Nithin, H.S.; Ramesh, M.R.
    In this study, NiCrC and NiCrSi coatings are deposited on the MDN 310 steel using High-Velocity Oxy-Fuel (HVOF) process. Laser Surface Melting (LSM) post-heat treatment is carried out on as-sprayed coatings using Laser Engineered Net Shaping (LENSTM) with a power of 300W. The characteristics of both coatings in terms of mechanical and metallurgical properties have been investigated. The thicknesses of the as-sprayed NiCrC and NiCrSi coatings are in the range of 170-200μm. Laser-treated NiCrC and NiCrSi coatings exhibit a thickness range of 162-185μm, respectively. The microstructure of laser-treated NiCrC-300W coating clearly shows a dendrite-like structure, whereas the laser-treated NiCrSi coating exhibits hard layer and columnar homogeneity. Microhardness of as-sprayed NiCrC coating is 515±15 HV0.3 and that of NiCrSi coating is 645±25 HV0.3. Microhardness of laser-treated NiCrC coating is 720±30 HV0.3 and that of NiCrSi coating is 890±15 HV0.3. Dry sliding wear tests are conducted at room temperature (RT) and 400°C with 10-N and 20-N loads. The wear rates at 400°C temperature of laser-treated NiCrC and NiCrSi coatings produced are slightly below (1-2.2)×10-3mm3/m and (0.8-1.6)×10-3mm3/m, respectively. Laser-treated coatings produced better dry sliding wear behavior compared with as-sprayed coatings owing to dense microstructure. Formation of SiC phase in NiCrSi coating imparts high wear and frictional resistance compared to the NiCrC coating. © 2022 World Scientific Publishing Company.
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    Development and Characterization of Biomedical Porous Ti–20Nb–5Ag Alloy: Microstructure, Mechanical Properties, Surface Bioactivity and Cell Viability Studies
    (Korean Institute of Metals and Materials, 2022) Shivaram, M.J.; Arya, S.B.; Nayak, J.; Panigrahi, B.B.
    Abstract: In this study, antibacterial Ag element added to synthesis of porous Ti–20Nb–5Ag (wt%) alloy using powder metallurgy space holder route. The microstructural, mechanical property, surface bioactivity and cytotoxicity behavior of porous Ti–20Nb–5Ag alloy have been investigated. The developed porous alloy obtained the porosities ranging from 22.5 to 68%. The porous sample having a porosity of about 43% is found to be in the optimum condition, which possess a modulus of about 5.8 GPa with an excellent compressive strength about 205 MPa. XRD result shows that the formation of small amount of α-Ti, β-Ti, along with α״ martensite and Ti2Ag are key phase constituents of sintered porous Ti–20Nb–5Ag alloys. The compression strength and elastic modulus of the sintered alloys were showed that decreased with increase of porosity. Surface bioactivity result revealed that the significant formation of hydroxyapatite on the alkali-heat treated (5 M NaOH) porous Ti–20Nb–5Ag alloy which is found after the in vitro test in SBF. Further, the cell viability test was conducted on as-synthesized porous Ti–20Nb–5Ag alloy for 1, 4, and 7 days using MG-63 human osteoblast cells and result shows an excellent cell proliferation, and the cytotoxicity test confirms the non-toxic nature of the porous alloy which is very much suitable for implant application. Graphic Abstract: [Figure not available: see fulltext.]. © 2021, The Korean Institute of Metals and Materials.
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    Development of titanium nitride thin film microheaters using laser micromachining
    (Elsevier Ltd, 2022) M.a, M.A.; Lakshmi Ganapathi, K.L.; Ambresh, M.; Nukala, P.; Udayashankar, N.K.; Mohan, S.
    In this paper, we report the fabrication and characterization of titanium nitride (TiN) thin-film-based microheaters. TiN thin films have been optimized on Si and SiO2 substrates for their optimum electrical resistivities by controlling the process parameters, including argon:nitrogen (Ar:N2) ratio in reactive pulsed DC magnetron sputter (PDCMS) deposition technique. An optical emission spectroscope (OES) was used for monitoring the plasma characteristics at various nitrogen flow rates. The microstructural and surface properties of the TiN films have been investigated and correlated with the electrical properties. It has been observed that the amount of nitrogen flux in the TiN plasma plays an essential role in the microstructural, surface, and electrical properties of the TiN thin films. Micro-heaters have been fabricated with TiN thin films with low electrical resistivity using laser engraving techniques instead of conventional lithographic and micromachining techniques. The TiN microheater has shown excellent performance. A temperature of 406 °C has been achieved by applying an input power of 8 W. This work paves the path for developing scalable and economic TiN microheaters using laser micromachining techniques. © 2021
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    Microstructural Study and Mechanical Characterization of ECAP Processed C70600 Alloy
    (Springer, 2022) Sachin, S.; Shivananda Nayaka, H.S.
    Copper–Nickel alloy C70600 was processed by equal channel angular pressing (ECAP), at room temperature, up to 8 passes, to study the mechanical properties and metallurgical behavior Microstructural studies showed grain refinement up to fourth ECAP pass. Microhardness value increased by 45% after 4 ECAP passes. With further increase in ECAP passes, samples attained a saturated state. Similar trend was observed in Ultimate tensile strength with an increase of 54% as compared to homogenized sample and reached a maximum value of 562 MPa. Increase in mechanical property was attributed to strengthening by grain refinement and dislocation strengthening. XRD analysis showed the absence of precipitate in the deformed specimens. © 2022, The Institution of Engineers (India).
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    Effect of zirconium oxide particulate composites with Al-Si on the microstructural and mechanical properties of hot pressed, spray forming and stir casting methods
    (Taylor and Francis Ltd., 2023) Patil, I.S.; Anarghya, A.; Rao, S.S.; Herbert, M.A.; Kushwaha, R.
    This research work aims to investigate the aluminum and silicon alloy reinforced with the ZrO2 powder particles, which has been fabricated using stir casting and spray deposition method. The mechanical properties, micro hardness and microstructure of the developed metal matrix composite is investigated. The microstructural results indicate that the rich interface among the AlSi-ZrO2 particles and depicts the agglomeration of reinforced phase resulting to poor wettability of ZrO2 and observed decohesion. The mechanical testing results indicate that the tensile strength increases with the percentage of ZrO2. Moreover, as cast composites exhibit reverse tendency in compressive and hardness values. The highest compressive values for as cast and hot-pressed composites were 380 MPa and 337 MPa for 10% ZrO2. The highest tensile strength of 191.83 MPa was obtained for 5% ZrO2 as cast composite and 164 MPa for 15% ZrO2 hot pressed composite. It is to note that as cast composite method represented more homogenous data compared to the hot-pressed composites. Hot pressed samples exhibited the reduction in the porosity compared to the as cast. The developed method proved to be accurate, reduced time and efficient to predict the numerous samples. © 2021 Engineers Australia.
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    Investigation of Microstructure and Mechanical Properties of Cast Al–10Zn–3.5Mg–2.5Cu Nanocomposite Reinforced with Graphene Nano Sheets Produced by Ultrasonic Assisted Stir Casting
    (Springer Science and Business Media Deutschland GmbH, 2023) Alipour, M.; Keshavamurthy, R.; Koppad, P.G.; Shakiba, A.; Reddy, N.C.
    Microstructure and mechanical properties of aluminum alloy Al–10Zn–3.5Mg–2.5Cu/graphene nanoplates composites produced by ball milling and stir casting have been investigated. The presence of dispersed Graphene nano plates with high specific surface area significantly increases the strength of the composites. The microstructural studies of the alloy revealed that graphene nano plates addition reduces the grain size, but adding higher graphene nano plates content (1 wt% graphene nano plates) does not change the grain size considerably. Further investigations on tensile tests revealed that the addition of graphene nano plates increases ultimate tensile strength. Samples under T6 heat treatment (heating up to 460 °C for 8 h, quenching in water (25 °C) and aging at 120 °C for 24 h) show better strength than other samples. At higher graphene nano plates contents, the presence of graphene agglomerate on grain boundaries was found to be the favored path for crack growth. The composite containing 0.7 wt% graphene nano plates exhibits tensile strength of 582 Mpa. © 2022, American Foundry Society.
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    Comparison of the Experimental and Modelling Results of Mechanical Characteristics of LM6 and LM9 Alloy for Tractor Application
    (Springer, 2023) Shetteppanavar, C.C.; Shinde, R.B.; Hanumanthappa, H.; Mohanraj, G.T.; Shanmugam, B.K.S.; Srivatsav, S.K.Y.; Kavitha Kumar, A.R.B.K.
    In India, the development of composite and alloys material has provided the required characteristics material. In this study, an attempt has been made to compare the performance of LM6 and LM9 alloy for an automobile application. These alloys are studied based on the tensile strength and fatigue test required for the pullet used in tractor application. The tensile test results showed that the LM9 alloy specimen has higher strength than the LM6 alloy specimen. Furthermore, results showed that the fatigue strength of the LM9 alloy specimen was found to be higher than the LM6 alloy specimen. Further, the tensile and fatigue materials behaviour of LM6 and LM9 specimens were compared through ANSYS modelling. From the experimental and modelling results, it was clear that the modelling results are in close agreement with the tensile and fatigue experimental results. The mechanical characteristics such as tensile and fatigue strength of the LM9 specimen were found to be much better than the LM6 specimen. The microstructural analysis also showed higher silicon particles providing higher strength for LM9 specimens than LM6 specimens. The pulley material made out of LM9 alloy will avoid the shear failure occurrence of the pulley. © 2022, The Institution of Engineers (India).