Department of Metallurgical & Materials Engineering

&ldquo;IIT Jodhpur is committed to impart quality education to facilitate the creation of qualified, competent and responsible human resources to meet the emerging technological challenges of the world. It is working towards creating an equitable learning platform that is positive, accessible and effective in the face of the modern societal and scientific advancements.

Flexibility in curriculum, in all its academic programs, encompassing elements of teaching, research, creativity, innovation and entrepreneurship is the most unique feature of IIT Jodhpur. The Department of Science and Technology (DST), under the National Mission on Cyber Physical Systems, has identified IIT Jodhpur as a Technology &amp; Innovation Hub in the area of Augmented Reality and Virtual Reality. The institute has also been nominated as the coordinator for the Jodhpur City and Knowledge Cluster by the Office of Principal Scientific Adviser, Government of India.

The sprawling 852-acre IIT Jodhpur campus is a majestic tribute to the deep-rooted diverse cultural heritage of the region. The campus is an architectural masterpiece, which is slated to become an international exemplar of sustainability with net-zero energy, and advanced water and waste management strategies.&rdquo;

IIT Jodhpur

In the present study, equiatomic CoCrFeMnNi high entropy alloy (HEA) was subjected to thickness reductions of 20, 40, and 60% during cold rolling in order to thoroughly investigate the evolutions of both the microstructure and the deformation texture. Important aspects of deformed microstructures such as the activation of multiple twin variants and the formation of shear bands in the matrix were captured using electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) techniques. Twin trace analysis (TTA) was performed in conjunction with resolved shear stress (RSS) analysis for the identification of active twin variants. The RSS ratio, which is a ratio of the maximum RSS values for corresponding twin and slip systems, was used to reveal the orientation dependence of deformation twinning. Visco-plastic self-consistent (VPSC) simulations were carried out to predict the evolution of the crystallographic texture, the transition routes of ideal orientations subjected to multiple deformation twinning, and the role that deformation modes play in the rotation of orientation. Experimental and simulation results substantiated the key finding of the deformation twinning of a Brass orientation, which established new perspectives concerning the evolution of microstructure and texture. One twin variant of the Copper orientation was moved to a Goss orientation by dislocation slip while the other two variants were rotated towards Brass and S orientations. Meanwhile, twin variants of the S and Brass orientations primarily transitioned to a Brass orientation. The Goss orientation showed great resistance to the twinning mode. Furthermore, dislocation slip and the formation of shear bands contributed to the evolution of a strong texture while deformation twinning had the opposite effect. © 2021 Elsevier Ltd.

World University root node

International Journal of Plasticity

Deformation mechanisms and texture evolution in high entropy alloy during cold rolling

In this work, the effect of crystallographic orientations and the strengthening due to grain/twin boundaries were investigated by uniaxial compression of single- and bi-crystal micropillars of pure zirconium (Zr) with ≥99.9% purity. Micropillars fabricated using focused ion beam (FIB) milling were compressed using a flat punch tip in a nanoindenter to obtain stress–strain curves for individual orientations of Zr. Only near-basal-oriented samples were deformed by multiple slip, while samples with other orientations were deformed by a single slip. Bi-crystal samples had significantly higher flow stress than single-crystal samples–the increment in flow stress arising from grain boundaries being higher than that arising from twin boundaries. Our analysis shows that while twin-boundary strengthening can be explained based on a size effect according to the Hall-Petch equation, the higher strengthening effect of grain boundaries appears to arise from a combination of a sample-size effect as well as dislocation accumulation at boundaries. © 2020 Informa UK Limited, trading as Taylor & Francis Group.

Philosophical Magazine Letters

Strengthening effect of grain and twin boundaries in zirconium bi-crystal micropillars

Fe2O3 hematite is a technologically important material with applications in energy storage as well as being the key phase formed in the rust of iron-based materials. Despite this central importance, there is much that is still unknown regarding the properties of defects in Fe2O3 and consequently oxide growth. Here, using screened hybrid density functional theory (HSE06), we consider the thermodynamics of vacancies in Fe2O3, considering the effects of ionic and electronic chemical potentials on both iron and oxygen vacancy formation. We find that, in the oxygen-rich limit, iron vacancies are easier to form, though the difference in formation energy between the two vacancies is only about 1 eV. In contrast, in the Fe-rich limit, oxygen vacancies have an extremely low formation energy, only 0.07 eV at mid-gap, and would spontaneously form as the Fermi level is reduced, while Fe vacancies require over 5 eV to form. Consistent with experiment, this indicates that Fe2O3 is relatively easily reduced but not oxidized. However, the theoretical picture is very different when considering other exchange-correlation functionals (GGA + U or SCAN), emphasizing the critical role of the exchange-correlation functional in describing this system accurately. © 2020 American Chemical Society.

The Journal of Physical Chemistry C

Correction to “Critical Assessment of the Thermodynamics of Vacancy Formation in Fe2O3 Using Hybrid Density Functional Theory”

Development of high capacity anode materials is one of the essential strategies for next-generation high-performance Li/Na-ion batteries. Rational design, using density functional theory, can expedite the discovery of these anode materials. Here, we propose a new anode material, germanium carbide, g-GeC, for Li/Na-ion batteries. Our results show that g-GeC possesses both benefits of the high stability of graphene and the strong interaction between Li/Na and germanene. The single-layer germanium carbide, g-GeC, can be lithiated/sodiated on both sides yielding Li2GeC and Na2GeC with a storage capacity as high as 633 mA h/g. Besides germagraphene's 2D honeycomb structure, fast charge transfer, and high (Li/Na)-ion diffusion and negligible volume change further enhance the anode performance. These findings provide valuable insights into the electronic characteristics of newly predicted 2D g-GeC nanomaterial as a promising anode for (Li/Na)-ion batteries. © 2020 The Authors

Journal of Power Sources

Thermodynamics and kinetics of 2D g-GeC monolayer as an anode materials for Li/Na-ion batteries

Chemistry

Trends in

After publication, the authors discovered two errors in the DFT data reported which partially affect Figures 2, 7, and 8. While these errors do not affect the main findings of this work, we wish to make sure these issues do not complicate future comparisons and so we have added this correction for publication. The first error is an issue with the applied oxygen-rich O2 reference state for SCAN calculations which affects the reported formation energy values of VO and VFe using this method. The value used was for the O2-molecule instead of per O, which thus introduced a factor of 2 error in the reference state for the O-rich SCAN cases. The updated formation energy values are given in the updated Figures 2 and 7 below. We note that this brings the SCAN calculation values more in line with the other approaches but the anomalous local magnetic structures noted in the original manuscript still remain and still preclude careful consideration of defects. (Figure Presented). © 2021 American Chemical Society. All rights reserved.

Journal of Physical Chemistry C

Erratum: Critical assessment of the thermodynamics of vacancy formation in Fe2O3using hybrid density functional theory (The Journal of Physical Chemistry C (2020) 124:43 (23988-24000) DOI: 10.1021/acs.jpcc.0c07522)

Al 4043 is commonly used as a filler material for welding of aluminium-based components. In the present research work, Al 4043/xTiB2 (titanium diboride) microcomposites (x = 2, 4, 6, 8 and 10 wt%) are fabricated by dilution of Al 4043/10TiB2 in situ master composites synthesized by salt-melt reaction. To synthesize the nanocomposites, in situ Al 4043/10TiB2 composites are re-melted, diluted and ultrasonic-treated for 5 min. The microstructural analysis revealed that ultrasonic treatment (UT) is beneficial on improving the dispersion and refinement of TiB2 particles. UT of Al 4043/2TiB2 composites reduced the size of TiB2 particles from ~ 1270 to ~ 25 nm. At the same time, the efficiency of UT on agglomerate breakage and particle size reduction decreases with the increase in amount of reinforcement. The hindrance generated by increased amount of reinforcements to ultrasonic wave propagation and allied impairment on cavitation implosion is proposed as the reason for the reduction in efficiency of UT. The mechanical property analysis revealed that UT-assisted size reduction and agglomerate breakage of TiB2 particles significantly increase both hardness and compressive strength of in situ composites. The results revealed that the compressive strength of TiB2-reinforced Al 4043/10TiB2 micro- and nanocomposite increased up to ~ 90 and ~ 150 MPa, respectively. Also, a significant improvement in hardness was observed in the reinforced Al 4043/10TiB2 micro- and nanocomposites by ~ 94% and ~ 98%, respectively, compared to the monolithic alloy. © 2021, King Fahd University of Petroleum & Minerals.

Arabian Journal for Science and Engineering

Effect of post-reaction ultrasonic treatment on synthesis, microstructural evolution and mechanical behaviour of Al 4043/TiB2 in situ nanocomposites

The present study has focused on the detailed dilatometric and electron microscopic analysis of the formation of austenite and its decomposition in two Cerium (Ce) modified steels containing 0.6 and 0.03 wt pct Ce. Despite a long incubation time, the austenite formation is very fast in the high-Ce steel (0.6 wt pct Ce) during heating. Whereas, the low-Ce steel (0.03 wt pct Ce) promotes early nucleation of austenite but shows a significant delay in the completion of the transformation. Similar trend has been observed for the decomposition of austenite during cooling; the low-Ce steel shows early start of transformation with a sluggish kinetics. The role of Ce on the overall transformation kinetics of austenite during the heating–cooling cycle has been investigated and discussed from thermodynamic viewpoint and nucleation probability. Engineering stress–strain curves have shown a better combination of strength and ductility in the low-Ce steel compared to the high-Ce one. Coarse and spherical Ce2O3 particles (average dia. ~ 4 µm) in grain interior along with the brittle and grain boundary elongated Ce-C/Ce-Fe intermetallic phases (length ~ 8 µm and width ~ 3 µm) are responsible for the lower strain hardening as well as an early failure of the high-Ce steel. Finally, the microstructure-tensile property correlation has been established using chemical composition and fractographic analysis. © 2021, The Minerals, Metals & Materials Society and ASM International.

Metallurgical and Materials Transactions A

Role of Cerium on Transformation Kinetics and Mechanical Properties of Low Carbon Steels

Fill factor (FF) deficit and stability is a primary concern and challenge with the perovskite solar cell. The band alignment and resistance at the junction interface further decreases the fill factor and thus limits the performance of the device. Moreover, degradation of the intrinsic properties of the upcoming perovskite material such as methylammonium lead halide on exposure to ambience or moisture creates instability and decreases the shelf life of the device. To overcome all these challenges, we have engineered the device structure and introduces an earth-abundant material in the primitive perovskite structure by introducing an inorganic hole transport layer (HTL). It was observed from the calculation that the FF is sensitive to the band offset values. Moreover, the band alignment/band offset role and effect at the Perovskite/HTL junction were investigated. It is evident from the calculation that the inorganic material replacing Spiro-MeOTAD can enhance the stability of the device by providing insulation from ambient. The efficiency of SnS and spiro-MeOTAD were found to be comparable in the present work and thus the shelf life and moisture sensitivity challenge of the perovskite solar cell is addressed. Moreover, this work paves the way for earth-abundant p-type chalcogenides tin selenide (SnS) as a HTL layer in the perovskite solar cell. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

Optical and Quantum Electronics

Computational analysis of chalcogenides as an inorganic hole transport layer in perovskite solar cells

Borophene, the lightest among all Xenes, possesses extreme electronic mobility along with high carrier density and high Young's modulus. To accomplish device-quality borophene, novel approaches of realization of monolayers need to be urgently explored. In this work, micromechanical exfoliation is discovered to result in mono- and few-layered borophene of device quality. Borophene sheets are successfully fabricated down to monolayer thickness. Distinct crystallographic phases of borophene viz. XRD study reveals crystallographic phase transition from rhombohedral to several other eigen phases of borophene. The role of the destination substrates is held crucial in determining the final phase of the transferred sheet. The exfoliation energy is calculated by density functional theory. Molecular dynamics simulations are used to simulate the exfoliation process. Heterolayers of borophene, with black phosphorene (BP) or with molybdenum disulfide (MoS2) atomic sheets, are found to result in photoexcited coupling quantum states. Gold-coated borophene bestows promising anchoring capability for surface-enhanced Raman spectroscopy (SERS). Successful demonstration of the electronic behavior of micromechanically exfoliated borophene and excitonic behavior of borophene-based heterolayers will guide future generation devices not only in electronics and excitonics, but also in thermal management, electronic packaging, hydrogen storage, hybrid energy storage, and clean energy solutions. © 2021 Wiley-VCH GmbH