Influence of upward and horizontal growth direction on microstructure and microhardness of an unsteady-state directionally solidified Al-Cu-Si alloy

In order to analyze the effect of the growth direction on dendrite arm spacing (λ1) and microhardness (HV) during horizontal directional solidification (HDS), experiments were carried out with the Al-3wt.%Cu-5.5wt.%Si alloy and the results compared with others from the literature elaborated for upwa...

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Bibliographic Details
Published in:	Matéria Vol. 21; no. 1; pp. 260 - 269
Main Authors:	Araújo, Raimundo Lucivaldo Marães de, Kikuchi, Rafael Hideo Lopes, Barros, André Santos, Gomes, Laércio Gouvea, Moutinho, Daniel Joaquim da Conceição, Gonçalves, Fernando de Almeida, Moreira, Antonio Luciano Seabra, Rocha, Otávio Fernandes Lima da
Format:	Journal Article
Language:	English
Published:	Rede Latino-Americana de Materiais 01-03-2016
Subjects:	CONSTRUCTION & BUILDING TECHNOLOGY MATERIALS SCIENCE, MULTIDISCIPLINARY METALLURGY & METALLURGICAL ENGINEERING Horizontal directional solidification Al-based multicomponent alloys Microstructure Microhardnees
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Summary:	In order to analyze the effect of the growth direction on dendrite arm spacing (λ1) and microhardness (HV) during horizontal directional solidification (HDS), experiments were carried out with the Al-3wt.%Cu-5.5wt.%Si alloy and the results compared with others from the literature elaborated for upward directional solidification (UDS). For this purpose, a water-cooled directional solidification experimental device was developed, and the alloy investigated was solidified under unsteady-state heat flow conditions. Thermal parameters such as growth rate (VL) and cooling rate (TR) were determined experimentally and correlations among VL, TR, λ1 and HV has been performed. It is observed that experimental power laws characterize λ1 with a function of VL and TRgiven by: λ1=constant(VL)-1.1 and λ1=constant(TR)-0.55. The horizontal solidification direction has not affected the power growth law of λ1 found for the upward solidification. However, higher values of λ1 have been observed when the solidification is developed in the horizontal direction. The interrelation of HV as function of VL, TR and λ1 has been represented by power and Hall-Petch laws. A comparison with the Al-3wt.%Cu alloy from literature was also performed and the results show the Si element affecting significativaly the HV values.
ISSN:	1517-7076 1517-7076
DOI:	10.1590/S1517-707620160001.0024