Evolution of elongated pores at the melt–solid interface during controlled directional solidification

Lee, C.P.; Anilkumar, A. V.; Cox, Matthew C.; Lioi, C.B.; Grugel, R. N.

doi:10.1016/j.actamat.2013.03.006

Cited by 17 publications

(4 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the contrary, the average diameters of the pores are not significantly changed by these two parameters, which are in the range of 93.4–134.7 μm. The result agrees well with the reported theoretical model, which suggested that the solidification rate plays a dominate role in the diameter of pores (all specimens in this study are prepared at the same solidification rate).…”

Section: Resultssupporting

confidence: 92%

Ultrahigh-Strength Porous Ceramic Composites via a Simple Directional Solidification Process

Zhao

Liu

et al. 2022

Nano Lett.

View full text Add to dashboard Cite

Porous ceramics possess great application potential in various fields. However, the contradiction between their pores and their strength have significantly hampered their applications. In this study, we present a simple directional solidification process that relies on its in situ pore forming mechanism to fabricate Al 2 O 3 /Y 3 Al 5 O 12 / ZrO 2 porous eutectic ceramic composites with a highly dense and nanostructured eutectic skeleton matrix and a lotus-type porous structure. The flexural strength of this porous ceramic composite with a porosity of 34% is 497 MPa at ambient temperature, which is a new record of the strength of all current porous ceramics. This strength can remain at 324 MPa when the temperature increases up to 1773 K because of its refined lamellar structure and strong bonding interface. We demonstrate an interesting application of the directional solidification in efficiently preparing the ultrahigh-strength porous ceramic with high purity. The findings will open a window to the strength of porous ceramics.

show abstract

Section: Resultssupporting

confidence: 92%

Ultrahigh-Strength Porous Ceramic Composites via a Simple Directional Solidification Process

Zhao

Liu

et al. 2022

Nano Lett.

View full text Add to dashboard Cite

show abstract

“…The first term on the right-hand side of equation ( 22) together with equation ( 23) implies the positive curvature of the solidification front. Based on observations [20], a nucleated bubble occurs at the concave region with the positive curvature between the bubble and the solid or the liquid on the solidification front. The curvature outside the concave region between the liquid and the solid on the solidification front is negative, which is contradictory to the scaling of the first term on the right-hand side of equation (22).…”

Section: Discussionmentioning

confidence: 99%

“…Slight modification of the solute concentration in the solid by the segregation between the liquid and the solid, Liu et al [13] calculated the porosity with the appropriate fitting parameters leading to the minimum supercooling criterion, and the agreement with the experimental results. The analytical solute concentration fields due to the irrelevant boundary conditions were, however, questioned by Drenchev et al [19], whereas the minimum supercooling criterion due to the incorrect sign of the curvature in Gibbs-Thomson boundary condition was also questioned by Lee et al [20].…”

Section: Introductionmentioning

confidence: 99%

Scaling of inter-pore spacing of lotus-type pores

2023

View full text Add to dashboard Cite

The present study is to scale the inter-pore spacing and bubble radius required for controlling the porosity of the lotus-type pores in the solid during a unidirectional solidification. The porosity in solid degrade properties of material in welding, casting and additive manufacturing, etc. On the other hand, the ordered cylindrical pores in the material are often used to improve the functional properties, such as the tensile and compression stresses, the impact and acoustic energy absorption, the permeability, and the thermal and electrical conductivity, etc. Different from the traditional minimum undercooling criterion to estimate the porosity and size of lotus-type pores, this study relevantly combines the Gibbs-Thomson equation, the Young-Laplace equation, the nucleation theory, and the Henry’s law or Sieverts’ law to scale the inter-pore spacing and the critical radius of the lotus-type pores, which are considered as the same order of the wavelength and the amplitude of the morphological instability of the solidification front, respectively. This work revises the minimum undercooling criterion which ignores the nucleating bubble on the solidification front, and conducts irrelevant evaluation of the curvature of the solidification front. The present work finds the revised scaling results and available experimental data to be in good agreement. The sizes of the pores and the porosity in the solid can be successfully controlled in advance.

show abstract

“…Based on the analytical solute concentration in liquids and the minimum undercooling criterion provided by the Jackson–Hunt model during eutectic solidification, Liu et al [ 10 ] predicted and experimentally confirmed decreases in porosity, pore radius, and inter-pore spacing as solidification speed, total gas pressure, and partial pressure of hydrogen and argon increased during the gasarite solidification of copper. The Jackson–Hunt theory and analytical solutions of solute concentration were, however, criticized by Lee et al [ 11 ], Drenchev et al [ 12 ], and Wei et al [ 13 ]. Lu et al [ 14 ] also provided a simple thermodynamic model to describe the relationship between processing variables and the pore structure for the ordered porosity copper fabricated via directional solidification.…”

Section: Introductionmentioning

confidence: 99%

Parametric Control via the Algebraic Expression of Lotus-Type Pore Shapes in Metals

Wang,

Lee,

Wei

et al. 2024

Materials

View full text Add to dashboard Cite

Lotus-type porous metals, characterized by low densities, large surface areas, and directional properties, are contemporarily utilized as lightweight, catalytic, and energy-damping materials; heat sinks; etc. In this study, the effects of dimensionless working parameters on the morphology of lotus-type pores in metals during unidirectional solidification were extensively investigated via general algebraic expressions. The independent dimensionless parameters include metallurgical, transport, and geometrical parameters such as Sieverts’ law constant, a partition coefficient, the solidification rate, a mass transfer coefficient, the imposed mole fraction of a solute gas, the total pressure at the top free surface, hydrostatic pressure, a solute transport parameter, inter-pore spacing, and initial contact angle. This model accounts for transient gas pressure in the pore, affected by the solute transfer, gas, capillary, and hydrostatic pressures, and Sieverts’ laws at the bubble cap and top free surface. Solute transport across the cap accounts for solute convection at the cap and the amount of solute rejected by the solidification front into the pore. The shape of lotus-type pores can be described using a proposed fifth-degree polynomial approximation, which captures the major portions between the initial contact angle and the maximum radius at a contact angle of 90 degrees, obtained by conserving the total solute content in the system. The proposed polynomial approximation, along with its working parameters, offers profound insights into the formation and shape of lotus-type pores in metals. It systematically provides deep insights into mechanisms that may not be easily revealed with experimental studies. The prediction of a lotus-type pore shape is thus algebraically achieved in good agreement with the available experimental data and previous analytical results.

show abstract

Evolution of elongated pores at the melt–solid interface during controlled directional solidification

Cited by 17 publications

References 10 publications

Ultrahigh-Strength Porous Ceramic Composites via a Simple Directional Solidification Process

Ultrahigh-Strength Porous Ceramic Composites via a Simple Directional Solidification Process

Scaling of inter-pore spacing of lotus-type pores

Parametric Control via the Algebraic Expression of Lotus-Type Pore Shapes in Metals

Contact Info

Product

Resources

About