Faculty Publications
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Item Influence of Refractory Elements on Mechanical Properties of High Entropy Alloys(Springer, 2021) Kumar Sinha, A.K.; Soni, V.K.; Chandrakar, R.; Kumar, A.High entropy alloys (HEAs) have become the most popular among the materials scientists and researchers due to their attributes like high strength, hardness and corrosion resistance when compared to conventional alloys. For sprawling use of HEAs in various domains such as aerospace, structural and automobile, it is necessary for researchers to explore more number of HEAs. In this endless endeavour of exploration, researchers have also developed refractory HEAs which possess better mechanical properties when compared to conventional HEAs. But, HEAs (without refractory elements) are more economical than refractory HEAs. This is due to the fact that most of the refractory elements are expensive. The present work focuses on the effect of refractory elements, namely, Mo, W, Ta, Nb, Ti and V on mechanical properties of HEAs. This review also provides an insight into the phase evolution in HEAs due to addition of refractory elements. Moreover, it also unfolds research gaps from past literature, which shows that there is scarcity of literature on dynamic characteristics, fatigue and creep analysis of Hf, Zr, Si and Cr based HEAs. © 2021, The Indian Institute of Metals - IIM.Item Phase Evolution of Novel MoNbSiTiW Refractory High-Entropy Alloy Prepared by Mechanical Alloying(Springer, 2022) Prakash, O.; Chandrakar, R.; Chandraker, S.; Rao, K.R.; Kumar, R.; Kumar, A.; Dubey, V.Refractory high-entropy alloys (RHEAs) are new types of material that have been developed for high-temperature applications. RHEAs should have enhanced high-temperature strength while maintaining a sufficient level of room-temperature toughness. The phase evolution of novel MoNbSiTiW RHEAs was investigated after mechanical alloying (MA) for 35 h. X-ray diffraction (XRD) was used to analyze the phase evolution, and analysis of particle morphologies was done using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). XRD results indicate that NbMoSiTiW RHEAs with up to 10 h of mechanical alloying have a stable solid solution phase with body centered cubic (BCC) structure. Further milling of NbMoSiTiW RHEAs promotes the evolution of intermetallic compounds until 35 h of mechanical alloying. The Williamson-Hall process was incorporated for crystalline size and lattice strain measurement and the results show that, after 35 h of mechanical alloying, the crystalline size decreased from 298 nm to 25 nm, and an enhancement in lattice strain was observed from 0.1% to 0.65%. © 2022, The Minerals, Metals & Materials Society.Item Effect of metalloid element on the microstructural and mechanical properties of AlCoCrCuFeNi high-entropy alloys(Taylor and Francis Ltd., 2024) Chandrakar, R.; Chandraker, S.; Kumar, A.; Jaiswal, A.The impact of the metalloid element silicon (Si) addition on the microstructural and mechanical properties of the AlCoCuCrFeNiSix high-entropy alloy system is examined in this paper. The alloys were synthesized using a vacuum arc melting route. X-ray diffraction was used to analyse the current high-entropy alloys’ phase formation to comprehend the alloying process’s behaviour. It is evident from the peak pattern of the X-ray diffraction that the inclusion of Si promotes the growth of body-centred cubic structures. The microhardness and wear resistance were increased by increasing the Si content from 0 to 0.9. Si presence enhances the hardness of the alloys and strengthens the grain boundary. Improved hardness and wear resistance results from the enhanced body-centred cubic-phase formation, which poses a barrier to the dislocation movement and prevents further deformation. Furthermore, the inclusion of Si improved corrosion resistance in potentiodynamic polarization measurements. Excellent compressive strength is possessed by all of the high-entropy alloys with Si addition. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Item Laser cladding technology for high entropy alloys: effect and applications(Institute of Physics, 2024) Prakash, O.; Chandrakar, R.; Martin, L.; Verma, J.; Kumar, A.; Jaiswal, A.A multi-component category of an alloy containing very specific properties revolutionized the area of material science and the present engineering era. Laser cladding, a technique for surface coating, enhances surface quality and modifies properties using advanced coating technologies. In current trends, Laser cladding is mainly used in equipment and machine parts for enhancing surface properties, repairing damaged parts and surface coating caused by its advantages such as small heat-affected zone, low substrate damage, low dilution rate and exceptional metallurgical material bonding among coating and used substrate. Laser cladding improves substrates’ mechanical and various functional-specific properties, ensuring a high-quality balance between mechanical and surface attributes. The research society was able to investigate laser-cladding HEAs coatings because of the superior attributes of HEAs compared to ordinary alloys. This paper reviews current developments in laser-cladding HEAs coatings and the application of laser-cladding technology to HEAs materials. The laser cladding high-entropy alloy coatings have potential applications in corrosion, wear, and oxidation resistance, as well as their respective substrates. Cladded coatings composed of HEAs materials are measured to have shown potential applications in recent technology, opening exciting possibilities for the future. The study also discusses current trends and future prospects. © 2024 The Author(s). Published by IOP Publishing Ltd.Item Investigation of phase transformation and mechanical properties of silicon addition on AlCrFeMnNi high entropy alloys(Institute of Physics, 2024) Chandrakar, R.; Chandraker, S.; Kumar, A.; Jaiswal, A.This paper examines the impact of silicon in the AlCrFeMnNi high-entropy alloy system, focusing on both its microstructural and mechanical properties. Alloys with varying silicon content (x = 0, 0.3, 0.6, 0.9 atomic ratio) were synthesized using vacuum arc melting. The phase formation of these high-entropy alloys was analyzed using x-ray diffraction to comprehend the alloying process behaviour. The findings revealed that the solidification of the AlCrFeMnNi alloy occurred in dendritically, with dendrite cores containing Cr, Fe, and Ni, while interdendritic regions were enriched in Al and Ni after adding Silicon. Increasing the silicon content from 0 to 0.9 led to significant improvements in microhardness and wear resistance. This improvement is attributed to the reinforcement of grain boundaries provided by silicon. The formation of an Al and Ni rich B2 phase is crucial in resisting dislocation motion and preventing further deformation. Additionally, the addition of silicon led to improved corrosion resistance, as demonstrated by potentiodynamic polarization measurements. However, a trade-off was observed between compressive strength and ductility: compressive strength increased with higher silicon concentrations, but at the expense of ductility. © 2024 The Author(s). Published by IOP Publishing Ltd.