Application of polarized light microscopy on microstructural characterization of semisolid slurry

Guo

et al. 2019

Materials

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The distribution homogeneity of grain size affects the fluidity of the semi-solid slurry, which in turn affects the properties of the casting. One key factor affecting grain size uniformity resides in the nucleation number, which has been studied thoroughly, while the other factor is temperature gradient which has not been investigated yet. In this study, the microstructure evolutions under certain temperature gradients are investigated by experiment and simulation using a two-dimensional quantitative phase-field (PF) model. A parallel and adaptive mesh refinement algorithm is adopted to solve the nonlinear phase-field equations. The results indicate that temperature gradient can affect the size distribution of microstructure in the semi-solid slurry prepared by the SEED process. A higher temperature gradient (in the range of 0.230~0.657 °C/mm) along the radial direction is beneficial to the homogeneity of the grain size in a slurry.

Section: Resultsmentioning

confidence: 99%

Effect of Temperature Gradient on the Grain Size Homogeneity of SEED Produced Semi-Solid Slurries by Phase-Field Simulation

Guo

et al. 2019

Materials

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“…Some common methods in China. Slurry preparation is the first and the most critical step for SSP [11][12][13]. Its primary target is to prepare high-quality slurry with uniformly dispersed fine globules, which exerts considerable influence on the performance of the final parts.…”

Section: Slurry Preparation Methodsmentioning

confidence: 99%

Progress of Semi-Solid Processing of Alloys and Composites in China

Gan

et al. 2022

SSP

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Following the rapid growth of the automotive and communication industries, components with high quality and low cost are eagerly desired in China. Various technologies have been developed in China to meet the demand, while semi-solid processing (SSP) of alloys and composites is one of the most successfully developed and practically applied technologies. The major SSP applied in China is the rheocasting in terms of the Swirled Enthalpy Equilibration Device (SEED) process. In this review, we start with a brief reviewing some common slurry preparation methods and recent innovations of the SEED process. Subsequently, we describe the general situation and some recent examples of successful development and applications of SSP in China. Lastly, the future directions in SSP of alloys and composites are highlighted in this frontier research field at the end of this review.

“…Liang et al [5] and Nafisi [6] found the use of grain refiners resulted in fine structure. Liang et al [7] and Lashkari et al [8] found low pouring temperature was beneficial for the formation of fine microstructure. No published literature to date has shown the effect of the coating on the slug microstructure.…”

Section: Introductionmentioning

confidence: 99%

Mold–Slug Interfacial Heat Transfer Characteristics of Different Coating Thicknesses: Effects on Slug Temperature and Microstructure in Swirled Enthalpy Equilibration Device Process

et al. 2019

Materials

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Application of a coating on a mold surface is widely used in the foundry industry. Changes in coating change the heat transfer at the mold–melt interface, which influences the microstructure of the casting. In this study, the effect of boron nitride coating thickness on the interfacial heat transfer and slug microstructure in the Swirled Enthalpy Equilibration Device (SEED) process was investigated. The temperatures of the semi-solid slug and mold were measured, and the interfacial heat transfer coefficient and heat flux of the mold–slug interface was estimated based on these data. Microstructures of the quenched slugs were also examined. The results indicated that the interfacial heat transfer coefficient decreased with an increase in coating thickness and was sensitive to a coating thickness of less than 0.1 mm. The interfacial heat flux decreased sharply at the early stage, and then slowed down as the swirling time increased and the coating thickened. The coating thickness affected the temperature evolution of the slug at the early stage of the SEED process. As the coating thickness increased from near zero to 1.0 mm, the grain size of the slug increased by ~20 µm and the globular structure of the slug transformed into a dendritic structure.