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    Emerging processing routes
    (De Gruyter, 2023) Prakash, O.; Kumar, R.; Tapas, V.; Kumar, A.; Naveen, B.
    High-entropy alloys (HEAs) are produced using a number of processing techniques. HEAs have been produced in a variety of materials, including films, dense solid castings, and powder metallurgy components. The three types of processing routes-melting and casting, powder metallurgy, and deposition techniques-can be broadly divided into three classes. In order to create HEAs in the form of rods, bars, and ribbons, melting and casting procedures have been used, along with equilibrium and nonequilibrium cooling rates. The vacuum arc melting, vacuum induction melting, and melt spinning processes are the most widely used melt processing methods. The primary solid-state processing method to create sintered goods has been mechanical alloying (MA), followed by sintering. The surface modification methods utilized to create both thin films and thick layers of HEAs on various substrates include plasma nitriding, cladding, and sputtering. This chapter provides a brief overview of the various synthesis and processing methods used to create HEAs. The processing pathways for equiatomic and nonequiatomic HEAs are comparable. © 2023 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.
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    The influence of microwave sintering on the tribological performance of powder metallurgy based aluminum cenospheres composites
    (Trans Tech Publications Ltd ttp@transtec.ch, 2015) Ananda Kumar, M.G.; Seetharamu, S.; Sampath Kumaran, P.; Nayak, J.
    The Metal Matrix Composites (MMCs) especially Aluminum based systems have unique advantages of having superior mechanical, chemical and electrical properties, in addition to light weight and high stiffness. In this work, composites comprising of Aluminum with varied concentrations of Cenospheres as reinforcement was produced by Powder Metallurgy (PM) route. The densification of the composites was effected both by conventional and Microwave (MW) sintering techniques. The microstructures of the sintered samples were observed through scanning electron microscope (SEM) and phases by x ray diffraction technique (XRD), followed by evaluation of tribological parameter namely slide wear behavior and solid particle erosion resistance. The densities and the Brinell hardness values for the samples were also evaluated. The results showed that microwave sintered samples exhibited higher hardness, lower erosion and slide wear loss. © (2015) Trans Tech Publications, Switzerland.
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    Effect of chromium addition on properties of sinter-forged Fe-Cu-C alloy steel
    (World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2018) Kulkarni, V.R.; Nayak, J.; Dabhade, V.V.
    The present work deals with sinter-forged powder metallurgical (P/M) steels alloyed with chromium by addition of ferrochrome powder, which allows a close control over the chromium contents of alloy steels. Chromium contents can be varied by adjusting appropriately weighed ferrochrome powder in the P/M mixtures. Fe-Cu (2%) and C (0.7%) is the base composition for this P/M alloy steel. Study with the addition of 0.5% and 3% chromium by weight in the form of ferrochrome powder is carried out. The P/M alloy steel of base composition with no chromium content is also prepared for comparative study. The paper deals with these three alloy steels formed by the sinter-forging technique of powder metallurgy. The results of hardness and wear in hardened and tempered condition are reported in the present work. © 2018 World Scientific Publishing Company.
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    Machining characteristics of multiwall-CNT reinforced Al/Al-Si composites using recurrence quantification analysis
    (2011) Gangadharan, K.V.; Umashankar, K.S.; Ravish; Desai, V.
    Aluminium (Al)/Aluminium alloy composites are emerging as very promising materials, especially in the fields of aerospace and automotive for their various attractive and technically demanding properties. Discontinuously reinforced aluminium metal matrix composites with reinforcements as nanoparticles of ceramics in general and carbon nanotubes in particular have emerged as the forerunner for a variety of general and special engineering and structural applications. In many of the fields where these materials find applications, machining is invariably required for getting correct geometries, dimensions and surface finish of the components. Hence, establishing the machining characteristics of these materials in terms of the deterministic nature of dynamic signals such as cutting force signals and vibration signals is very important and sought after. Machining process has been understood to be nonlinear and chaotic in nature. In this paper a relatively new technique called Recurrence Plots (RP) and Recurrence Quantification Analysis (RQA), a tool to analyse nonlinear and chaotic systems, is used to study the machining characteristics of cast and powder metallurgy Al and Al-Si alloys (LM6 and LM25), CNT reinforced Al/Al-Si composites produced by powder metallurgy route. Cutting force signals were sensed, acquired and analysed using RQA technique. Determinism (DET), which is one of the variables of RQA, indicates the determinism present in a signal. The values of DET were used to compare the machining characteristics. For all the three materials the deterministic nature of the cutting force signal was highest when reinforced with 0.5 weight percentage CNT, followed by respective base alloys produced by powder metallurgy method and casting route. © 2011 Jordan Journal of Mechanical and Industrial Engineering.
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    Titanium foam with coarser cell size and wide range of porosity using different types of evaporative space holders through powder metallurgy route
    (Elsevier Ltd, 2014) Mondal, D.P.; Patel, M.; Das, S.; Jha, A.K.; Jain, H.; Gupta, G.; Arya, S.B.
    Ti-foams were made using different evaporative types of space holders such as acrowax and ammonium bicarbonate with a wide range of porosities (55-89%) through powder metallurgy technique. Cold compaction pressure was varied from 100 to 200. MPa in order to examine the effect of cold compaction pressures on the absolute porosities of the foams. The cell size, cell wall thickness and porosities of the foams were characterised as a function of cold compaction pressures and type of space holders. Empirical correlation has been established to predict foam porosities from compaction pressures and volume fraction of space holder. The sintered foams were found to be free from residue of the space holder. However, approximate 8-10% of titanium oxidized during sintering. The foam made with acrowax, as space holder attains slightly higher strength, modulus and energy absorption. © 2014 Elsevier Ltd.
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    The effect of the particle shape and strain rate on microstructure and compressive deformation response of pure Ti-foam made using acrowax as space holder
    (Elsevier Ltd, 2015) Mondal, D.P.; Patel, M.; Jain, H.; Jha, A.K.; Das, S.; Dasgupta, R.
    Titanium foams of varying amount of porosities have been made using acrowax bits as a space holder through powder metallurgy route. Two types of Ti-particles were used: (i) angular and (ii) spherical in order to see the effect of particle shape on microstructure and deformation behavior. The compressive deformation behavior of Ti-foams with varying porosities and type of particles are studied under different strain rates. It is observed that the microstructural characteristics of Ti-foam varied marginally with the shape of Ti-particles. But the shape of particles influenced reasonably the deformation responses of Ti-foam. The plateau stress, modulus and energy absorption follow power law with relative density irrespective of shape of Ti-particles. All these parameters in Ti-foams are almost invariant to the strain rate. The empirical constants associated with different empirically developed power law relations are different for different shape of Ti-particles. © 2014 Elsevier B.V.
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    Evaluation of mechanical properties for nickel based steel produced by metal injection moulding and sintered through conventional and microwave method
    (Italian Association of Chemical Engineering - AIDIC aidic@aidic.it, 2018) Veeresh Nayak, C.; Ramesh, M.R.; Desai, V.; Kumar Samanta, S.K.
    Metal injection moulding is a near net shape manufacturing technique. It developed from traditional plastic injection moulding and powder metallurgy process. The process involved mixing of metal powder and binder, injection moulding, debinding and sintering of moulded samples. Microwave process indicated critical consideration towards exceptional highlights, regards to, heating and sintering the various grouping of metals with the huge preferred perspective, control rate, and similarity, low ecological dangers. The samples consist of SS316L+WC-CrC-Ni metal powder and binders, low-density polyethylene (LDPE), paraffin wax (PW), stearic acid (SA) and polyethylene glycol (PEG 600). In the present study, the injection moulded green parts are exposed to high-intensity microwave fields operates at a frequency of 2.45 GHz. for sintering of MIM samples. The whole process time of the microwave-assisted sintering was remarkably less than conventional sintering. The sintering of SS316L+WC-CrC-Ni compact showed better results than those produced by sintering with conventional heating. The current study evaluates the effect of the conventional and microwave sintering on mechanical properties. © © 2018, AIDIC Servizi S.r.l.
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    Effect of heat treatment on properties of sinter forged Fe-Cu-C-Cr steel
    (Zibeline International Publishing Sdn. Bhd., 2019) Kulkarni, V.R.; Nayak, J.; Dabhade, V.V.
    Powder metallurgy is industrially well appreciated manufacturing technique. Many components are now manufactured by powder metallurgical route than conventional manufacturing techniques. It is customary for wrought steels to compare the properties of alloy in austempered condition with that in hardened and tempered condition. However limited data is available for austempered powder metallurgical components. In this work sinter forging technique is used to prepare samples from metal powders and subjected to austempering as well as conventional hardening and tempering heat treatments. Effect of these heat treatments on the microstructure, hardness and wear properties of Fe-2Cu-0.7C-2Cr sinter forged alloy are studied. From the results it is concluded that though hardness in hardened and tempered condition is lower (26 HRc) than that of austempered condition (39 HRc) its wear performance is better. © 2019 Rockefeller University Press. All rights reserved.
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    Evaluation of Wear Behaviour of Metal Injection Moulded Nickel Based Metal Matrix Composite
    (Springer Netherlands rbk@louisiana.edu, 2019) Veeresh Nayak, V.N.; Ramesh, M.R.; Desai, V.; Kumar Samanta, S.K.
    Metal injection moulding (MIM) is a near-net shape manufacturing technology for producing intricate parts, cost-effectively. MIM comprises combined techniques of plastic injection moulding and powder metallurgy. The present study focused on the development of the binder and fabrication of defect free MIM component. A wax-based binder system consisting of paraffin wax (PW), low density polyethylene (LDPE), polyethylene glycol (PEG-600) and stearic acid was established for MIM of NiCrSiB (70% Wt.) + Cr3C2-NiCr (30% Wt.) nickel based metal matrix composite (NMMC) powder. The feedstock was characterised through rheological properties at different temperatures. Injection temperature was determined from the rheological investigation of the feedstock having the 56% powder loading and 44% binder by volume. Sintering process was carried out with the temperature cycle in the range of 1250–1300 ?C under hydrogen purged atmosphere. The MIM components showed good and acceptable shrinkage in linear dimensions. The mechanical properties and wear behaviour of NMMC was studied using a pin-on-disc apparatus with alumina disc.Tests were performed under dry sliding conditions at room temperature and elevated temperatures of 200 and 400 ?C. Results shows that wear rate is maximum at 400 ?C for 40 N and lowest at room temperature for 10 N. Further wear mechanism was analysed using scanning electron microscope (SEM). © 2018, Springer Science+Business Media B.V., part of Springer Nature.
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    Sintering metal injection molding parts of tungsten-based steel using microwave and conventional heating methods
    (SAGE Publications Ltd info@sagepub.co.uk, 2019) Veeresh Nayak, C.; Ramesh, M.R.; Desai, V.; Kumar Samanta, S.K.
    In recent years, the near net shape metal injection molding process combines desirable features of plastic injection molding and powder metallurgy processes to gain high strength-to-weight ratio for manufacturing complex-shaped parts. The metal injection molding process consists of mixing, molding, debinding, and sintering. Microwave processing has attracted much attention in global research because of its unique features such as its ability to heat and sinter a wide variety of metals and its significant advantages in energy efficiency, processing speed, and compatibility. Also, it presents few environmental risks and can produce refined microstructures. The injected samples to be sintered are composed of fine tool steel metal powder and binders, stearic acid, paraffin wax, low-density polyethylene, and polyethylene glycol (600). In recent years, microwave-assisted post-treatment is considered a novel method for processing green parts. In this work, the green parts are subjected to high-intensity microwave fields which operate at a frequency of 2.45 GHz. Metal injection molding compacts were sintered using multi-mode microwave radiation. The sintering of a metal injection molding compact by microwaves has hardly been reported. The metal injection molding compact showed better results than those produced by sintering with conventional heating. This study evaluates the effect of conventional sintering and microwave sintering on mechanical properties. By optimizing the sintering process, increased sintered hardness, a more homogeneous microstructure, and greater shrinkage were obtained using microwave-assisted sintering. © IMechE 2018.