Faculty Publications
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Item The Effect of Cooling Rate and Cerium Melt Treatment on Thermal Analysis Parameters and Microstructure of Hypoeutectic Al-Si Alloy(Wiley Blackwell, 2015) Vijayan, V.; Prabhu, K.In the present investigation, pure cerium ingots were added to Al- 8% Si alloy melt to study its effect on the microstructure and cooling curve parameters. The melt treated alloy was solidified against sand base, stainless steel, brass, and copper chills to study the effect of chilling. Ce treated alloys solidified against sand base resulted in refinement of the eutectic silicon along with the formation of Al-Si-Ce ternary intermetallic compound. Addition of Ce to alloys solidified against chills resulted in the complete modification of eutectic silicon. Thermal analysis results revealed that the nucleation temperatures of eutectic silicon decreased on addition of cerium to the chilled alloys due to the synergistic effect of chilling and cerium addition. The degree of modification achieved was higher due to the decrease in the formation of Ce intermetallic s at higher cooling rates. © 2015 The Minerals, Metals & Materials Society. All rights reserved.Item The effect of cooling rate and cerium melt treatment on thermal analysis parameters and microstructure of hypoeutectic Al-Si alloy(Minerals, Metals and Materials Society 184 Thorn Hill Road Warrendale PA 15086, 2015) Vijayan, V.; Prabhu, K.In the present investigation, pure cerium ingots were added to Al-8% Si alloy melt to study its effect on the microstructure and cooling curve parameters. The melt treated alloy was solidified against sand base, stainless steel, brass, and copper chills to study the effect of chilling. Ce treated alloys solidified against sand base resulted in refinement of the eutectic silicon along with the formation of Al-Si-Ce ternary intermetallic compound. Addition of Ce to alloys solidified against chills resulted in the complete modification of eutectic silicon. Thermal analysis results revealed that the nucleation temperatures of eutectic silicon decreased on addition of cerium to the chilled alloys due to the synergistic effect of chilling and cerium addition. The degree of modification achieved was higher due to the decrease in the formation of Ce intermetallics at higher cooling rates.Item Effect of heat treatment on pitting corrosion resistance of 6061 Al/SiCP composite coated by the cerium oxide film in 3.5 N NaCl solution(2011) Rajasekaran, S.; Udayashankar, N.K.; Nayak, J.One of the main drawbacks of 6061 Al/SiCP composite is its poor pitting corrosion resistance in the aggressive environment containing chloride ions, such as seawater, for example. The present article deals with the investigations of effects of aging on the corrosion behavior of 6061 Al/SiCP composite and of the heat treatment on the pitting corrosion resistance of 6061 Al/SiCP composite coated by cerium oxide prepared by chemical bath technique. Potentiodynamic polarization test was used to study the corrosion behavior of cerium oxide coatings in 3. 5N NaCl solution. The microstructure of cerium oxide was examined by scanning electron microscopy (SEM) and the formed phases were identified by X-ray diffraction (XRD). The pitting corrosion resistance of the cerium oxide coating was found to be improved after heat treatment at 300°C for 30 min. © 2011 Allerton Press, Inc.Item The effect of the addition of strontium and cerium modifiers on microstructure and mechanical properties of hypereutectic Al-Si (LM30) alloy(ASTM International, 2013) Vijayan, V.; Ravi, M.; Prabhu, K.The present work deals with the melt treatment of LM30 hypereutectic Al-Si alloy using cerium and strontium and the assessment of its effect on microstructure and properties of the alloy. The addition of cerium simultaneously modified both primary and eutectic silicon, leading to an increase in ultimate tensile strength, as well as the wear resistance of the alloy. It was found that the coefficient of thermal expansion of the alloy decreased on modification of the microstructure. © 2013 by ASTM International.Item Computer aided cooling curve analysis and microstructure of cerium added hypereutectic Al-Si (LM29) alloy(Springer India sanjiv.goswami@springer.co.in, 2014) Vijayan, V.; Prabhu, K.Thermal analysis of LM29 alloy and Ce added LM29 alloys was carried out. The effect of cerium addition on solidification parameters and microstructural features of hypereutectic Al-Si (LM29) alloy was studied using Newtonian analysis technique. Thermal analysis parameters such as primary and eutectic phase nucleation and solidus temperatures were determined. The addition of Ce to LM29 alloy decreased the nucleation temperature of primary silicon and eutectic silicon. The microstructural examination of Ce added LM29 alloys revealed the presence of a polyhedral shaped Al-Si-Ce compound that might have caused the refinement of primary and eutectic silicon. The dendrite coherency point temperature of LM29 alloy was found to be suppressed on addition of Ce. © 2014 Indian Institute of Metals.Item Effect of chilling and cerium addition on microstructure and cooling curve parameters of Al-14%Si alloy(Maney Publishing maney@maney.co.uk, 2015) Vijayan, V.; Prabhu, K.Al-14%Si alloys, with and without cerium, were cast at varying cooling rates by solidifying them in a crucible and against chills. The effect of melt treatment and chilling on microstructure and cooling curve parameters of the alloy was assessed. Ce treated alloys solidified in clay graphite crucible at a slow cooling rate showed refinement of primary silicon and the formation of Al-Si-Ce ternary intermetallic compound. The addition of Ce to the alloy solidified against chills resulted in simultaneous refinement and modification of primary and eutectic silicon. Nucleation temperatures of both primary and eutectic silicon decreased on addition of cerium. The formation of the intermetallic compound decreased with increase in cooling rate, leading to the modification of the eutectic silicon. The increase in the degree of modification of the eutectic Si was associated with the decrease in the volume fraction of the intermetallic compound formed. © 2015 Canadian Institute of Mining, Metallurgy and Petroleum Published by Maney on behalf of the Institute.Item Hydrous Cerium Oxide Nanoparticles Impregnated Enteromorpha sp. for the Removal of Hexavalent Chromium from Aqueous Solutions(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2016) Selvasembian, S.; Selvaraju, N.; Raj Mohan, B.; Muhammed Anzil, P.K.; Amith, K.D.; Ushakumary, E.R.A novel nanobiocomposite, hydrous cerium oxide nanoparticles impregnated Enteromorpha sp. (HCONIE) was used effectively for the adsorption of Cr(VI) from aqueous solutions. The chemical and structural characteristics of the nanobiocomposite were investigated using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. Adsorption studies were determined as a function of pH, contact time, initial concentration of Cr(VI), HCONIE dose, and temperature. The equilibrium adsorption data were modeled using two parameter isotherms, including Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin, Jovanovic, Halsey, and Harkin-Jura. Adsorption data were well described by the Freundlich and Halsey isotherm. The kinetics data were analyzed using adsorption kinetic models like the pseudo-first-order, pseudo-second-order and intraparticle diffusion equation. Kinetic data showed good agreement with the pseudo-second-order kinetic model. The obtained thermodynamic parameters showed that the adsorption of Cr(VI) onto the HCONIE was exothermic in nature. The presence of foreign ions showed a decreased effect on the adsorption capacity of HCONIE towards Cr(VI) removal. The desorption study was carried out with 0.1 and 0.5 M of three different desorbing agents. The study suggests that HCONIE nanobiocomposite could be used for the removal of Cr(VI) from aqueous solution. © 2015 American Society of Civil Engineers.Item The effect of simultaneous refinement and modification by cerium on microstructure and mechanical properties of Al-8% Si alloy(Taylor and Francis Ltd. maney@maney.co.uk, 2016) Vijayan, V.; Prabhu, K.N.The effect of cerium melt treatment on microstructure and mechanical properties of gravity die cast Al-8% Si alloy was studied. The addition of Ce transformed the large columnar ?-Al grains into fine equiaxed grains and modified the acicular eutectic Si into fine fibrous form. The addition of Ce resulted in the formation of needle-shaped complex Ce intermetallic along the grain boundaries. Electrical conductivity measurements are used for the first time to reveal the effect of Ce addition on modification of the eutectic Si. The electrical conductivity of the alloy increased with Ce melt treatment. Scanning Electron Microscopy results suggests that the Ce particles did not heterogeneously nucleate the ?-Al grains, instead the fine equiaxed grains were formed through an invariant reaction between the liquid melt and Ce phase. The ultimate tensile strength, % elongation and hardness of the alloy significantly improved due to simultaneous modification and refinement. © 2016 Informa UK Limited, trading as Taylor & Francis Group.Item Development and characteristics of accumulative roll bonded Mg-Zn/Ce/Al hybrid composite(Elsevier Ltd, 2017) Anne, G.; Ramesh, M.R.; Shivananda Nayaka, H.; Arya, S.B.; Sahu, S.Accumulative roll bonding (ARB) process have been used develop Mg-2%Zn/Ce/Al hybrid composite and microstructure, mechanical and corrosion properties were investigated. The electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) revealed that the grains are significantly reduced and reaches up to 1 ?m in Mg-2%Zn layer and 1.8 ?m in Al layer having high angle misorientation of grain boundaries after subjected to 5-passes of the ARB process. The Al17Mg12, AlMg4Zn11 and Al11Ce3 intermetallic phases were observed through the XRD analysis. Mechanical properties of the hybrid composite improved with increase in the number of ARB passes which is attributed to work hardening, grain refinement and uniform distribution of Ce particles. Presence of Ce in the hybrid composite restricts the phenomenon of dynamic recrystallization and prevents the grain growth during ARB process. The corrosion rate of Mg-Zn/Ce/Al hybrid composite (0.72 mm/y) improved about 3.3 times as compared to that of Mg-2%Zn alloy (2.37 mm/y). © 2017 Elsevier B.V.Item Thermal Analysis of Cerium-Treated Chill-Cast Al-23 Si Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Vijayan, V.; Prabhu, K.N.The influence of elemental cerium addition on the cooling curve parameters and microstructure of hypereutectic Al-23Si alloy was investigated in this work. The cooling rate of the treated and untreated alloy samples was varied by solidifying the melt against chills of different materials in a stainless-steel tube. The cooling curve was recorded and nucleation temperatures of various phases in the alloy were measured. The results show that the chilling improves the effectiveness of the modifier. The two main phases of the alloy, primary silicon and eutectic silicon, were nucleated at temperatures of about 661.2 and 571.6 °C, respectively. The addition of Ce to slowly cooled alloys resulted in an increase in undercooling temperature of both the phases, with a decrease in its nucleation temperature, whereas the same additions increased the nucleation temperatures in chilled alloys. Based on the thermal analysis results, a relation between thermal analysis parameter (? TG) and silicon particle size of the alloy was proposed. © 2018, ASM International.