A study of the coarsening of liquid-solid mixtures using synchrotron radiation microradiography

Boettinger, William J.; Voorhees, Peter W.; Dobbyn, R. C.; Burdette, Harold E.

doi:10.1007/bf02648812

Cited by 18 publications

(12 citation statements)

References 5 publications

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“…In contrast, the insoluble Fe, Mn-containing particles will be present in the semisolid state and are of a size where they can potentially obstruct the migration of the liquid boundary, either through a pinning type mechanism or through inhibiting diffusion through the liquid from one boundary position to another [18]. The results are essentially consistent with the observations in [19][20][21][22] about the inhibiting effect of second phase particles. In modified alloy 2014, minor elements such as Fe, Mn, Si, which form insoluble intermetallic phases, have been stripped out and the coarsening is much faster.…”

Section: Dendrite Arm Coalescence In the Early Stages For Cooling Slosupporting

confidence: 82%

Microstructural coarsening of semi-solid aluminium alloys

Atkinson

Liu

2008

Materials Science and Engineering: A

162

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Semisolid metal processing involves processing metallic alloys between the solidus and the liquidus. The microstructure must be non-dendritic and consist of spheroids of solid in a liquid matrix. Two potential routes to suitable starting material are recrystallisation and partial melting (RAP) and cooling slope (CS). Here the microstructural coarsening of such materials in the semi-solid state is compared with rates in the literature.A slightly lower coarsening rate was observed for RAP route 2014 alloy with 37% fraction liquid than for CS route 2014 alloy with 17% fraction liquid despite the higher fraction liquid for the former. For the CS route, an increase in fraction liquid gave a higher coarsening rate.A relatively high coarsening rate was observed in a modified 2014 alloy with the Fe, Mn and Zn stripped out of the composition and a relatively low Si content. The coarsening rate was also relatively high for alloy 201 prepared by the CS route compared with alloy 2014 either by RAP or CS. It is likely that relatively low coarsening rates are associated with the presence of particles which are inhibiting the migration of liquid film grain boundaries, either through a pinning mechanism or through impeding diffusion through the liquid film at the boundary.

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Section: Dendrite Arm Coalescence In the Early Stages For Cooling Slosupporting

confidence: 82%

Microstructural coarsening of semi-solid aluminium alloys

Atkinson

Liu

2008

Materials Science and Engineering: A

162

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“…Another problem relates to the assumed diffusion field around each grain [87]. Observations show each grain exhibits a growth or shrinkage trajectory that depends on its local environment, not on the mean field [88]. In spite of these several difficulties, LPS grain size converges to a self-similar distribution, independent of the starting particle size distribution [89].…”

Section: Grain Size Distributionmentioning

confidence: 99%

Review: liquid phase sintering

2009

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Liquid phase sintering (LPS) is a process for forming high performance, multiple-phase components from powders. It involves sintering under conditions where solid grains coexist with a wetting liquid. Many variants of LPS are applied to a wide range of engineering materials. Example applications for this technology are found in automobile engine connecting rods and high-speed metal cutting inserts. Scientific advances in understanding LPS began in the 1950s. The resulting quantitative process models are now embedded in computer simulations to enable predictions of the sintered component dimensions, microstructure, and properties. However, there are remaining areas in need of research attention. This LPS review, based on over 2,500 publications, outlines what happens when mixed powders are heated to the LPS temperature, with a focus on the densification and microstructure evolution events.

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“…Thirty-five years later, Boettinger et al performed an in-situ study of the kinetics of grain growth in a thin foil of Al-Sn using time-resolved radiography. [39] We have revisited the Al-Sn system using the modern variant of stereoscopic X-ray radiographynamely, X-ray microtomography-which permits bulk samples to be studied with uniformly high resolution in all directions (rather than only in the plane parallel to the Xray detector). [6,21] Our measurements find that segregation in this material occurs highly nonuniformly, with some grain boundaries only partially decorated and others entirely unwet by Sn, resulting in incomplete visualization of the network of grain boundaries.…”

Section: Introductionmentioning

confidence: 99%

Quantitative characterization of the three-dimensional microstructure of polycrystalline Al-Sn using X-ray microtomography

Döbrich

Rau

Krill

2004

Metall Mater Trans A

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Characterizing the three-dimensional topology of grain-boundary networks in polycrystalline materials is a crucial step in the modeling of properties that depend on the sample microstructure. Using absorptioncontrast X-ray microtomography, we have carried out a large-scale microstructural characterization of polycrystalline Al doped with 2 at. pct Sn, which is immiscible in Al in the solid state. The segregation of Sn to the grain boundaries imparts a strong contrast in X-ray attenuation that can be reconstructed tomographically; however, the nonuniformity of the segregation process presents a formidable challenge to the automated segmentation of the reconstructions. By employing an iterative grain-finding algorithm followed by a novel grain-boundary-network optimization routine (based on a phase-field simulation of grain growth), we were able to extract reliable values for the size and topology of nearly 5000 individual grains in polycrystalline Al-Sn. The distributions and averages of these data deviate significantly from the corresponding microstructural parameters of the three-dimensional (3-D) Poisson-Voronoi tessellation often used to model polycrystalline samples. Much better agreement was observed with microstructures generated by the computer simulation of three-dimensional grain growth.

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A study of the coarsening of liquid-solid mixtures using synchrotron radiation microradiography

Cited by 18 publications

References 5 publications

Microstructural coarsening of semi-solid aluminium alloys

Microstructural coarsening of semi-solid aluminium alloys

Review: liquid phase sintering

Quantitative characterization of the three-dimensional microstructure of polycrystalline Al-Sn using X-ray microtomography

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