Sustainable Manufacturing and Foundry Practices
1CSIR-Central Mechanical Engineering Research Institute, Durgapur, West Bengal, India
2Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
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Semi-solid metal processing offers a compelling alternative to conventional casting by enabling the production of alloys with superior, non-dendritic microstructures. Slurry flow dynamics, less porosity formation, higher die and tool life, and final mechanical characteristics are all controlled by primary phase morphology during partial solidification. This review presents a critical assessment of microstructural evolution and mathematical modelling of alloys during semi-solid processing. The observed interaction between solid fraction development, morphological changes, slurry rheology and various semi-solid slurry generation techniques is highlighted. Various techniques for generating non-dendritic structures are provided, covering their working principles, comparative advantages, limitations and effective processing windows. Experimental studies remain constrained in fully capturing microstructure-property relationships and the influence of critical processing parameters. To provide a comprehensive assessment, the latest advancements in volume-averaged solidification process modelling have been examined, with explicit discussion of why interface-tracking methods such as phase-field models and Eulerian-Lagrangian approaches fall outside the present scope. Current two-phase and three-phase solidification models are evaluated with respect to heterogeneous nucleation, solute redistribution, interfacial heat transfer, and inter-phase momentum coupling. Discrepancies between numerical predictions and experimental observations are discussed, particularly under conditions of high shear and non-uniform thermal fields. The review demonstrates that computational constraints continue to limit the prediction of nucleation kinetics and microscale features, especially for high-temperature, high-Si and multi-element alloy systems. Although several formulations demonstrate practical potential in laboratory and small-scale industrial castings, further progress requires improved calibration, consistent closure relations, benchmark validation, and expanded material databases capturing micro-macro interactions. Addressing scale-up requirements related to process stability, defect control, tool life and feedstock consistency remains critical for enabling reliable semi-solid processing on an industrial scale.
Semi-solid metal processing, microstructural evolution, non-dendritic structure, mathematical modelling, solidification
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