On the Natural Convection in the Columnar to Equiaxed Transition in Directionally Solidified Aluminum-based Binary and Multicomponent Alloys

Materials Research

Carlos Henrique Ursolino Gomes¹  Rafael Hideo Lopes Kikuchi¹  André Dos Santos Barros¹  José Nazareno Santos Da Silva¹  Maria Adrina Paixão De Sousa Da Silva¹  Antonio Luciano Seabra Moreira¹  Otávio Fernandes Lima Da Rocha¹ 

关键词: columnar to equiaxed transition;    horizontal directional solidification;    thermal parameters;    transient conditions;    Al-Cu-Si alloys;   

DOI  :  10.1590/1516-1439.036315

来源: SciELO

【 摘 要 】

In order to investigate the effect of natural convection in columnar to equiaxed transition (CET), Al-3.0wt.%Cu and Al-3.0wt.%Cu-5.5wt.%Si alloys ingots were obtained during the transient horizontal directional solidification (THDS). Aiming to analyze the effect of superheat in the formation of the macrostructure in ternary Al-Cu-Si alloy, the experiments were conducted with three superheat temperatures above the liquidus temperature of the ternary alloy. A water-cooled solidification experimental device was used. Continuous temperature measurements were made during solidification at different positions in the casting and the data were automatically acquired. Thermal analysis has been applied to determine the thermal parameters such as growth rate (VL), cooling rate (TR) and temperature gradient (GL), whose values have been interrelated with the CET. The observation of the macrostructures has indicated that the resulting thermosolutal convection combined with superheat seem to favor the transition, which did not occur in a single plane, for all ingots obtained, i.e., it has been seen in a range of positions in ingots. The addition of Si element in binary Al-Cu alloy anticipates the CET. A comparison with experimental results for CET occurrence in different growth directions has been carried out.

【 授权许可】

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