Effects of Solidification Rate in the Microstructure of Al-Si5Cu3 Aluminum Cast Alloy

Abstract

Aluminium alloy Al-Si5Cu3 (319) is one of the most commonly used casting alloys for automobile components, due to its casting characteristics. Iron is the major impurity element that influences the detrimental β-phase formation in secondary aluminum alloys. In the present study, we investigated the influence of the cooling rate on the formation of iron compounds, α-Al 15 (Mn,Fe) 3 Si 2 and β-Fe 5 AlSi phases, in Al-Si5Cu3 containing 1.0% Fe, 0.5% Mn and 0.2% Mg, by thermal analysis and metallography. The results show that the high cooling rates, between 10-10 3 K/s, are able to reduce and nullify the formation of needle-like β-Al5FeSi phase, and help the formation of the Chinese scripts α-Al 15 (Fe,Mn) 3 Si 2 phase. The analysis of the curves reveals that the increase of the cooling rate increases the temperature of nucleation of the α-Al dendrite and decrease the eutectics Al-Si and Al-Cu phases.

The Effects of Heat Treatment on the Microstructure and Tensile Properties of an HPDC Marine Transmission Gearcase

“…The darker grey, continuous phase as shown in Figures 2-5 was observed in all samples and typically occupied the majority of the samples' surface area. The morphology and composition of this phase indicates that it is the primary α-Al phase, which is consistent with the literature on similar alloy compositions [15][16][17]. The laminated structure (alternating dark and light grey phase) was also observed in all samples.…”

“…The morphology and composition of this phase indicates that it is the Al-Si eutectic phase. Previous findings in the literature mention that this phase has various morphologies and compositions depending on the alloying elements present [15,18,19]. The blocky, fibrous structure of the Si particles corresponds well with the as-cast microstructure of Al-Si alloys.…”

Study of Porosity in Heat Treated Aluminum 319 Alloys.

“…1.D. The behavior of the samples with dwell time of 6 hours is due to the cooling rate, higher cooling rates favor the formation of α-Al 15 (Fe,Mn) 3 Si 2 , while slow cooling rates favor the formation of β-Al 5 FeSi as reported by Farina et al [5] It was concluded that over solution heat treatments successfully allow to obtain porosity in 319 aluminum alloys, however higher temperatures can be employed in order to maximize pore size. Dwell time showed a big influence in secondary phases' transformation since α-Al 15 (Fe,Mn) 3 Si 2 and β-Al 5 FeSi are only present with duel time of 6 hours.…”

A Continuous Casting Device with Electromagnetic Stirring for Production of SSM Feedstock Using Al-Si Alloys

“…40,41 , making synchronization a challenge when manual pouring is used. Furthermore, heat transfer between ingot, mould and environment should be sufficient to prevent excessive grain growth and allow a sufficiently thick, solid shell to form and the mushy zone (where solid and liquid coexist in the solidifying ingot) to develop a substantial coherent volume, i.e., a solid matrix substantial enough to bear the extraction load [42][43][44] . Application of a conductive coating (e.g., graphite) or use of a highly conductive alloy as mould material could help to accelerate solidification 45,46 .…”