Faculty Publications
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Item Modification of eutectic silicon in Al-Si alloys(2008) Hegde, S.; Prabhu, K.N.The mechanical properties of Al-Si alloys are strongly related to the size, shape and distribution of eutectic silicon present in the microstructure In order to improve mechanical properties, these alloys are generally subjected to modification melt treatment, which transforms the acicular silicon morphology to fibrous one resulting in a noticeable improvement in elongation and strength. Improper melt treatment procedures, fading and poisoning of modifiers often result in the structure which is far from the desired one. Hence it is essential to assess the effectiveness of melt treatment before pouring. A much investigated reliable thermal analysis technique is generally used for this purpose. The deviation from the standard curve in thermal analysis helps in assessing the level of refinement of the Si structure. In the present review an attempt is made to discuss various aspects of modification, including mechanism, interaction of defects and non-destructive assessment by thermal analysis. © 2008 Springer Science+Business Media, LLC.Item Effects of Phosphorus Treatment on Cooling Behavior, Heat Transfer, Microstructure, and Mechanical Properties of Hypereutectic Al-23%Si Alloy(Springer, 2025) Vijayan, V.; Prabhu, K.N.The influence of phosphorus (P) treatment on the microstructure, cooling behavior, interfacial heat flux, and mechanical properties of hypereutectic Al-23 Si alloy is investigated in the present work. Computer-aided cooling curve analysis revealed that higher cooling rates suppressed silicon cluster agglomeration and promoted nucleation of primary silicon at lower undercooling. The addition of P increased the nucleation temperature of primary silicon and resulted in finer silicon crystals. Eutectic silicon nucleation was facilitated by P treatment, with refined primary silicon acting as nucleation sites. Interfacial heat flux analysis demonstrated that P addition decreased the heat flux, attributed to the presence of less conductive primary silicon, and unmodified eutectic silicon microstructure. Microstructural analysis revealed the refinement of primary silicon and transformation of its morphology to polyhedral shape with P treatment. Heat treatment improved tensile properties, with refined primary silicon and copper precipitation contributing to enhanced strength. The morphology and composition of copper intermetallic varied with P and Cu content, influencing mechanical properties. These findings provide insights into optimizing alloy compositions and processing conditions for hypereutectic Al-Si alloys in various industrial applications. © ASM International 2023.