Precipitation in an A356 foundry alloy with Cu additions - A transmission electron microscopy study

Abstract

The influence of different Cu addition levels on the age hardening and precipitation behaviors in an Al356 foundry alloy during artificial aging treatments has been systematically studied. A detailed characterization of the precipitates at the atomic scale has been done by using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM). At peak hardness, the number density of needle shape precipitates increases with increasing Cu content, while the dominant hardening precipitates change from β in the Cu-free alloy to L and Q' phases in the Cu-added alloys. It is discovered that the cross section of a large fraction of L-phase contains an inversion centre, predominantly at the central Si atomic column in the lattice. It was also observed that some β precipitates incorporate Cu atoms at the Si 3 -sites in the β -molecule. In addition to the Mg-Si-(Cu) precipitates, a large fraction of nano-sized Si particles also precipitated in all the three alloys during artificial aging, which is attribute to the excess Si in solid solution.

Understanding of surface segregation of Cu and Zn on nano Si precipitates to the mechanical property improvement of high pressure die casting Al9Si3CuFe alloy

“…In addition, the habit plane for Si precipitate is identified as {111} Si that is parallel to {010}Al, at which an OR can also be recognized with the adjacent Al matrix: {111}<01-1> Si // {010}<001> Al . The OR between Si and Al matrix is in agreement with the results reported by Mørtsell et al [27]. The third type of Si precipitates viewing along <111> Si is presented in Fig.…”

“…For binary Al-Si alloy, it is reported that Si usually precipitate on {111} Al [29] which having an incoherent Si/Al interface. Whilst with elemental segregation on Si precipitate [27], it tends to precipitate on {010} Al leading to form a semi-coherence interface instead. The presence of segregation seems acting as a misfit reliever [30], and suppressing misfit dislocation at the interface [31].…”

Copper-Coated Graphene Nanoplatelets-Reinforced Al–Si Alloy Matrix Composites Fabricated by Stir Casting Method

“…Regarding the influence of the addition of Cu on the silicon phase, previous literature has given various opinions on this: Mørtsell et al [29] found that the addition of 1.0 wt% Cu into A356 alloy decreased the Si size. The phenomenon was explained with quenching vacancies: Cu and Si both have a high affinity for vacancies, and the addition of a solute with high affinity for vacancies (Cu) in the matrix contributes to the precipitation of the silicon phase.…”

Geometrical Parametric Optimisation of A356 Alloy Composite in a Two-Stage Casting Process for Automobile Wheel Covers using Response Surface Methodology

“…Furthermore, there is an increasing environmental threat that engine blocks pose to the environment. Engine blocks are not biodegradable and the use of organic biodegradable materials as reinforcements in A356 alloy composite has not been exploited [5,[10][11][12]. So, to what extent has the disposed engine blocks (i.e.…”