Effect of Heat Treatments on the Microstructure, Hardness and Corrosion Behavior of Nondendritic AlSi9Cu3(Fe) Cast Alloy

Abstract

In this paper we studied the influence of heat treatments on properties of AlSi9Cu3(Fe) nondendritic cast alloy. Solution heat treatment, six hours at 520 °C, while making the grains more spherical modifies corrosion morphology into intergranular corrosion and corrosion surrounding spherical particles in 3 % NaCl solution. Past solution treatment, quenching at 520 °C after one hour with two weeks of natural aging transform the shape of grains into equiaxes form. Two weeks of natural aging and 30 minutes of aging at 150, 200, 250 °C after solution treatment and quenching give birth to the "Chinese script" form of the Al 15 (MnFe) 3 Si intermetallic particles. The prolongation of the duration period of aging to one hour at 200 °C is sufficient to transform the morphology of corrosion into located corrosion by pitting, and a longer aging cancels the "Chinese script" form.

Corrosion Behaviour of Recycled Aluminium AlSi9Cu3(Fe) Machining Chips by Hot Extrusion and Thixoforming

“…The distribution of Si is not close to any element (except in some places where it coincides with Fe, Mn, and Cr), which indicates the presence of eutectic Si particles. So, according to the results obtained and in agreement with the literature, the formation of Al 2 Cu and various Fe-containing phases (AlFeSi, Al(Fe,Mn,Cr)Si) with Si is possible [37][38][39][40][41]. The greatest surface damage has been observed in the vicinity of intermetallic phases rich in Cu and Fe, which is associated with a higher oxygen content (i.e., the formation of Al 2 O 3 due to the Al dissolution).…”

“…They found that corrosion starts at the interface between the α-Al matrix and the Fe-rich IMCs due to microgalvanic corrosion processes. A similar influence of IMCs on the localised forms of corrosion of Al alloys was observed by Akiyama et al [38], Brunner et al [39], and Zazi [40]. Monticelli et al [41] point out that the potential differences between IMCs and the α-Al matrix in the AlSi9Cu3(Fe) alloy can reach up to 400 mV, leading to an intense corrosion attack and localised corrosion forms.…”

“…As can be seen, TFS has a round, globular microstructure with an average globule size of about 50 µm (Figure 2c). It is well known that the microstructure of various Al-Si alloys contains a matrix of dendritic α-Al surrounded by a eutectic (or polyhedral) Si phase and various secondary phases or IMCs, which are additionally enriched with Fe and Cu [37][38][39][40][41]. Such a complex structure has a significant influence on the mechanical and corrosive properties of the tested material.…”

Corrosion behavior of primary and secondary AlSi high pressure die casting alloys

“…However, they cannot be used for other applications like safety relevant structural pieces, because of the difficult removal of iron and copper during the recycling of scrap that causes a decrease of the final component's properties. [11] In detail, the presence of β-iron precipitates causes a very low ductility, not acceptable for these classes of components. In addition, either iron or copper precipitates strongly reduces corrosion resistance that is another fundamental item required in this field.…”

Microstructural, morphological characterization and corrosion behavior of sand cast AlSi10Cu(Fe) alloy in chloride solution

“…The α-aluminum phase represents the matrix of cast aluminum-silicon alloys; it crystallizes in the appearance of non-faceted dendrites (Warmuzek 2004), and sometimes in appearance of non-dendritic forms (Zazi 2013). Moreover, the hard primary silicon particles distributed in the matrix are responsible for the good mechanical properties and the high wear resistance (Elzanaty 2015).…”