Inverse Analysis of Eutectic Nucleation and Growth Kinetics in Hypoeutectic Al-Cu Alloys

Abstract

The nucleation and growth kinetics of equiaxed eutectic grains in hypoeutectic Al-Cu alloys has been investigated numerically and experimentally. Three-dimensional geometries of eutectic/ primary phases obtained by X-ray microtomography (XMT) have been used to generate computational domains for use with a eutectic transformation model. The samples for XMT analysis were extracted from a series of small-scale castings of Al-20 wt pct Cu solidified with different cooling rates to obtain a variety of microstructures. The stochastic nucleation technique has been coupled with a deterministic cellular automaton (CA) model to simulate the nucleation and growth of eutectic grains within the interdendritic network characterized by the XMT analysis. An inverse analysis approach has been employed to quantify the deterministic nucleation and growth relationships in the eutectic solidification model. Metallographic measurements of eutectic size and density made on cast samples solidified with a variety of cooling rates and quenched at different times after the start of the eutectic transformation were used in the inverse analysis. The current approach provides a realistic description of eutectic grain evolution in multicomponent alloys.

Directing Substrate Morphology via Self-Assembly: Ligand-Mediated Scission of Gallium–Indium Microspheres to the Nanoscale

“…Copper indium gallium diselenide (CIGS) solar absorbers and gallium–indium nitride (Ga x In 1– x N) are both cases where stoichiometric control is critical, and the ability to control the composition of complex materials over broad ranges is an important goal. − Photonic structures composed of nanoscale photovoltaics could be used to trap light in a material and to improve electrical conversion efficiency while minimizing the materials consumed by (and the cost of) a device . Microscale eutectic or amorphous metallic glass domains that form within metal alloys are responsible for the microscale structure and macroscale properties of many commercial alloys. , Micro- and nanoscale uniform alloy particles may be designed and then incorporated into an alloy to exert control over the structure and properties of materials in a way natural solidification may not allow. Further, by designing new molecules for self-assembly, it is possible to incorporate different functionality and interaction strengths in the film while guiding and controlling nanoparticle size and shape.…”

Effect of Cooling Rate on the Dendrite Coherency Point During Solidification of Al2024 Alloy

“…However, high potential substrates for nucleation, e.g., TiAl 3 and TiB 2 , cause to increase the nucleation rate of primary a-Al phase. [31,32] The solid fraction at the DCP of Al2024 alloy is given in Table IV. The effect of adding 0.06 wt pct Ti element and different cooling rates on the solid fraction at the DCP is shown in this Table. At a constant cooling rate, solid fraction at dendrite coherency of grain-refined samples is higher than samples with no grain refiner.…”

Permeability of dual structured hypoeutectic aluminum alloys

“…In a recent study by the authors [29] N v of 90 mm À3 and higher were achieved using a similar material, i.e. Al-20 wt.% Cu, and casting procedure.…”

“…Although the dendritic structure is initially nonsymmetric due to the stochastic nature of the solidified dendritic structure, by applying these boundary conditions to the domain the effect of growing eutectic grains that may enter the domain is considered. For the sake of brevity the reader is referred to Khajeh and Maijer [29] for a detailed description and assessment of the CA model employed in this study.…”