Title: Influence of Fe on the microstructure and mechanical properties of low Al-SI alloys

Authors: Antonio Pancho; Carlos Díaz; Oscar Sotomayor

Addresses: Materials Engineering Department, Escuela Politécnica Nacional, Ladrón de Guevara E11•253, 170517, Quito-Ecuador ' Materials Engineering Department, Escuela Politécnica Nacional, Ladrón de Guevara E11•253, 170517, Quito-Ecuador ' Materials Engineering Department, Escuela Politécnica Nacional, Ladrón de Guevara E11•253, 170517, Quito-Ecuador

Abstract: The present study investigates the influence of iron (precipitation of Fe-rich phases) on microstructure, ultimate tensile strength, elongation after fracture and hardness of the aluminium alloy A356, for which metallographic analysis and testing of mechanical properties were performed for iron weight percentages of 0.5, 0.8 y 1%. Phases identification was carried out by X-ray diffraction, which revealed the precipitation of β iron intermetallic phase of stoichiometry Al₅FeSi and monoclinic crystal structure. Cooling rate (0.45°C/s) for sand mould was calculated through secondary dendrite arm spacing whose average length was 62.75 μm. Microhardness measurements showed the hard nature of the β phase, which produced a general increase on the alloy's hardness. The tensile strength reduced slightly (~11% for 1 wt. % Fe) unlike the fracture elongation (ductility) which suffered greatly reduces with iron increase (~54% for 1 wt. % Fe).

Keywords: Fe influence on AL; β phase; A356.

DOI: 10.1504/IJMMP.2018.097216

International Journal of Microstructure and Materials Properties, 2018 Vol.13 No.5, pp.317 - 330

Received: 02 Mar 2018
Accepted: 29 Jun 2018
Published online: 04 Jan 2019 *

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