Journal Articles
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Item Review of microstructure evolution in hypereutectic Al-Si alloys and its effect on wear properties(2014) Vijayan, V.; Prabhu, K.Al-Si alloys with silicon content more than 13 % are termed as hypereutectic alloys. In recent years, these alloys have drawn the attention of researchers due to their ability to replace cast iron parts in the transportation industry. The properties of the hypereutectic alloy are greatly dependent on the morphology, size and distribution of primary silicon crystals in the alloy. Mechanical properties of the hypereutectic Al-Si alloy can be improved by the simultaneous refinement and modification of the primary and eutectic silicon and by controlling the solidification parameters. In this paper, the effect of solidification rate and melt treatment on the evolution of microstructure in hypereutectic Al-Si alloys are reviewed. Different types of primary silicon morphology and the conditions for its nucleation and growth are explained. The paper discusses the effect of refinement/modification treatments on the microstructure and properties of the hypereutectic Al-Si alloy. The importance and effect of processing variables and phosphorus refinement on the silicon morphology and wear properties of the alloy is highlighted. © 2013 Indian Institute of Metals.Item A comprehensive review of friction stir welding parameters on Ti-6Al-4V alloy microstructure and mechanical properties(Taylor and Francis Ltd., 2025) Rao, R.N.; Rao, S.S.; Vijayan, V.Ti-6AL–4 V alloy, is a widely recognised titanium alloy. It is responsible for over half of all applications involving titanium alloys, primarily due to its attractive mechanical and physical properties that make it a highly desirable material. For most applications, the vast majority of working components require permanent joining. The conventional fusion welding of titanium often leads to oxidation losses and increased brittleness. Friction stir welding improves weld quality by preventing heating the metal past its melting point. Despite the fact that Friction Stir Welding (FSW) of Ti6Al4V alloys has advantages over other welding methods, the process parameters have a major impact on the weld microstructure and mechanical properties. In most cases, a defect-free weld with the ideal microstructure can be achieved by selecting the best process parameters, such as the tool material, tool geometry, traverse speed, and rotational speed. This paper briefly reviews Ti-6Al-4 V alloy friction stir welding developments and understandings. Variation in friction stir welding process parameters like tool rotation and translation speed affects weld region microstructure constituents, defects, and mechanical properties. This paper establishes a crucial relationship between process variables, microstructure, defects, and mechanical properties. Summarising and tabulating recent developments for easy understanding and adoption is emphasised. © 2024 Informa UK Limited, trading as Taylor & Francis Group.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 The Effect of Addition of Ce and Sr on the Solidification Path of Al–8Si–2Cu Alloy(Springer India sanjiv.goswami@springer.co.in, 2015) Vijayan, V.; Prabhu, K.Thermal analysis of Al–Si alloys is very useful for the non-destructive evaluation of the melt quality. The present work aimed at the study of the effect of addition of Ce and Sr on cooling curve parameters, microstructure and mechanical properties of Al–8Si–2Cu alloy. The thermal analysis parameters of melt treated alloys were determined. The addition of Ce influenced both primary and eutectic phase nucleation temperatures, whereas, Sr affected only the eutectic nucleation temperature. The depression in the eutectic arrest temperature was higher with Sr addition when compared to Ce. Consequently, a high degree of modification was achieved with Sr. The addition of Ce yielded fine equiaxed ?-aluminium grains and Sr treatment resulted in columnar grains. The mechanical properties of the alloy significantly improved on simultaneous addition of Ce and Sr. The individual addition of Sr, Ce and combined addition of Ce + Sr to base alloy increased the tensile strength by about 40, 52 and 83 % respectively. © 2015, The Indian Institute of Metals - IIM.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 The Effect of Chilling and Ce Addition on the Microstructure and Mechanical Properties of Al-23Si Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Vijayan, V.; Prabhu, K.The present work involves the study of the effect of varying concentration of Ce addition on microstructure and mechanical properties of Al-23%Si alloys. Melt-treated alloys were solidified in copper, brass, stainless steel molds to assess the effect of cooling rate. The effect on microstructure was assessed by measuring the fineness of primary silicon and eutectic silicon particle characteristics. The Ce melt treatment transformed the coarse and irregular primary silicon into refined polyhedral silicon crystals, and the effect was more significant at higher cooling rates. Although the melt treatment had refined the eutectic silicon at lower cooling rates, it did not show any considerable effect on the eutectic silicon at higher cooling rates. The mechanical properties of the alloy increased significantly with increase in cooling rates and cerium concentration. Analysis of the results and literature reveals that the refined primary silicon was formed as a result of an invariant reaction between Ce compounds and primary silicon at higher temperatures. © 2016, ASM International.Item Corrosion behavior of high and low temperature austempered ductile iron (ADI) in iron ore slurry(ASTM International, 2017) Aithal, P.M.; Vijayan, V.; Surendranathan, A.O.; Udupa, K.R.; Samuel, K.G.Corrosion behavior of austempered ductile iron (ADI) and forged EN31 steel balls in a ground iron ore slurry was studied as a function of time in the slurry, while the microstructure of ADI developed due to different tempering temperature and tempering time. The corrosion rates of the grinding balls immersed in the iron ore slurry were determined using electrochemical analysis and weight loss methods. It was found that the pH of the iron ore slurry increased with time and the corrosion behavior was influenced by the pH of the slurry. The corrosion rate of forged EN31 steel balls increased with the increase in time and pH of the slurry, whereas the corrosion rate of ADI balls depended on the austempering treatment. In general, the forged EN31 steel ball offered better corrosion resistance than ADIs during the early stages of exposure in the slurry (low pH values of the slurry), but at higher pH values of the slurry, the ADIs yielded better corrosion resistance than forged EN31 steel balls. The ADI austempered at higher temperatures showed better corrosion resistance than the ones austempered at lower temperatures. © © 2017 by ASTM International.Item The effect of Sr modification on thermal diffusivity of Al–8Si alloy(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Vijayan, V.; Prabhu, K.N.Newtonian and Fourier analysis techniques were used to calculate the solid fraction and latent heat during the solidification of Al–8Si alloy and the subsequent results were used to study the effect of Sr modification on thermal diffusivity of the solidifying melt. The results indicate that the thermal diffusivity increased significantly with increase in Sr content. The increase in the thermal diffusivity was attributed to the increase in the electronic conduction of the modified alloy due to the decreased activity of the bifilm. The results also indicate that the latent heat evolved during solidification increased with increase in Sr concentration and was associated with the increase in the solidification range that occurred during the modification process. © 2017 Informa UK Limited, trading as Taylor & Francis Group.