Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy

Abstract

Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy.

Ultrahigh strength and plasticity in laser rapid solidified Al–Si nanoscale eutectics

“…Enhanced plasticity in room temperaturerolled nanolamellar Al-Al 2 Cu [14] was attributed to slip transmission enabled by orientation relationship. In the ternary Al-Al 2 Cu-Si system, increased plasticity was attributed to bimodal morphology [15,16], whereas in commercial A356 hypoeutectic Al-Si alloy [17], the flow strength was increased to ≈ 300 MPa using aging heat treatment to produce nanoscale precipitates. This study is focused on the understanding of deformation mechanisms that enable high flow strength and uniform plasticity in nanoscale eutectic morphologies.…”

Numerical analysis of the influence of distributed inhomogeneities on tangential fretting

“…Al-Sibased casting alloy is widely used in modern aerospace and automobile industries for complex-shape components. In the present work, Si particles of approximately spherical shape, with weight percentage of 7.0 wt.% distributed in the casting alloy, 46 as shown in Figure 18(b), can be viewed as stiff inhomogeneities (Si particles have a larger Young's modulus than that of the aluminum) in the matrix.…”

Strength-ductility trade-off via SiC nanoparticle dispersion in A356 aluminium matrix

“…Very recently, researchers [66,67] reported strength-ductility trade-off for A356 aluminum alloy. Some impressive results were obtained in their study.…”