An Alternative to the Recycling of Fe-Contaminated Al

Autor: Crystopher Brito, Noé Cheung, Manuel V. Canté, Thiago Soares Lima, Amauri Garcia, José E. Spinelli
Rok vydání: 2018
Předmět:
Zdroj: Journal of Sustainable Metallurgy. 4:412-426
ISSN: 2199-3831
2199-3823
DOI: 10.1007/s40831-018-0188-y
Popis: Iron is considered an unavoidable impurity in Al–Si alloys, since it is collected during melting and casting operations. This is particularly critical when scraped and recycled materials are used. Excessive iron can reduce the mechanical properties. This is explained by the formation of Fe-bearing intermetallic particles, since the alloy properties are deeply related to their type, size, and amount within the microstructure. The effects of Ni addition on the microstructure of impure Al–Si alloys have not been established so far. As such, the present investigation examines Fe- and Fe/Ni-containing Al–9 wt% Si alloys. Two directionally solidified (DS) alloys are investigated: the Al–9 wt% Si–0.5 wt% Fe (nonmodified) and Al–9 wt% Si–0.5 wt% Fe–0.5 wt% Ni (Ni-modified) alloys. The focus is to determine solidification conditions (i.e., cooling rate, TR; and growth rate, VL) as well as Fe- and Fe/Ni-containing Al–9Si alloys that will yield particular volume fractions, sizes and shapes of Fe-bearing intermetallics. Considering a certain limit of the dendritic microstructure scale (i.e., λ1 > 100 μm), it is shown that the ultimate tensile strength of the Al–9Si–Fe–Ni alloy is higher than that of the Al–9Si–Fe alloy and quite close to that of an Al–9Si alloy, that is, the beneficial effect of Ni addition on providing lower fraction and more compacted Fe-bearing intermetallics has counterbalanced the deleterious effect of the Fe contaminated aluminum on the tensile strength. The elongation-to-fracture, however, only approaches that of the Al–9Si alloy for the smallest λ1 values, which are associated with the highest solidification cooling rates.
Databáze: OpenAIRE
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