Science Links Japan | Prediction of Casting Structures for Alminum Base Alloys Using Heterogeneous Nucleation Parameter

Prediction of Casting Structures for Alminum Base Alloys Using Heterogeneous Nucleation Parameter

Accession number;05A0086020

Title;Prediction of Casting Structures for Alminum Base Alloys Using Heterogeneous Nucleation Parameter

Author; NISHIGUCHI NORITAKA (Hokkaido Univ., Graduate School of Engineering, JPN) OSASA KEN'ICHI (Hokkaido Univ., Graduate School of Engineering, JPN)

Journal Title;Journal of Japan Foundry Engineering Society

Journal Code:G0096A

ISSN:1342-0429

VOL.77;NO.1;PAGE.3-8(2005)

Figure&Table&Reference;FIG.13, TBL.1, REF.11

Pub. Country;Japan

Language;Japanese

Abstract;For the purpose of the prediction of casting structures, the heterogeneous nucleation rate in the undercooled melt of solidifying Al-Si alloys was evaluated by comparing experimentally observed macrostructures of solidified ingots with numerically simulated ones. Molten alloys were unidirectionally solidified in an adiabatic mold from a steel chill block located at the bottom of the mold. The top of the mold was heated with an electric furnace to prevent the alloys from nucleation at the melt surface. In the experiment, columnar to equiaxed transition and subsequent equaxed to columnar transition (CECT) were observed. Numerical simulation for the macrostructure formation of the sample ingots was carried out using a cellular automaton (CA) method, and heterogeneous nucleation rate in the solidifying alloys was evaluated by producing structures similar to experimental ones. The heterogeneous nucleation rate was expressed as a probabilistic function with an exponential form of undercooling that determines the probability of nucleation event in simulation, and the value of the exponent was regarded as a heterogeneous nucleation parameter. The heterogeneous nucleation parameter of Al-Si alloy increased with increase in initial solute content of the alloy. An attempt was made to predict the macrostructure of conventional cast ingot using the evaluated heterogeneous nucleation parameter and the simulation predicted macrostructures composed of columnar and equiaxed crystals similar to experimentally observed ones. (author abst.)

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