A Comparative Study on the Microstructures and Mechanical Properties of Al-10Si-0.5Mg Alloys Prepared under Different Conditions

Abstract

Fabrication condition greatly influences the microstructures and properties of Al alloys. However, most of the available reports focus on a single fabrication technique, indicating there is still a lack of systematic comparisons among wider ranges of fabrication methods. In this paper, with conventional casting (via sand/Fe/Cu mold) and additive manufacturing (AM, via selective laser melting, SLM) methods, the effects of cooling rate (Ṫ) on the microstructures and mechanical properties of hypoeutectic Al-10Si-0.5Mg alloy are systematically investigated. The results show that with increasing cooling rate from sand-mold condition to SLM condition, the grain size (d) is continuously refined from ~3522 ± 668 μm to ~10 μm, and the grain morphology is gradually refined from coarse dendrites to a mixed grain structure composed of columnar plus fine grains (~10 μm). The eutectic Si particles are effectively refined from blocky shape under sand/Fe-mold conditions to needle-like under Cu-mold conditions, and finally to fine fibrous network under SLM condition. The tensile yield strength and elongation is greatly improved from 125 ± 5 MPa (sand-mold) to 262 ± 3 MPa (SLM) and from 0.8 ± 0.2% (sand-mold) to 4.0 ± 0.2% (SLM), respectively. The strengthening mechanism is discussed, which is mainly ascribed to the continuous refinement of grains and Si particles and an increase in super-saturation of Al matrix with increasing cooling rate.

Effects of Aging Treatments on the Age Hardening Behavior and Microstructures in an Al-Mg-Si-Cu Alloy

“…Upon undergoing artificial aging for a short period of time, Al-Mg-Si-(Cu) alloys exhibit a substantial increase in hardness. This hardening phenomenon stems from the formation and dispersion of a large number of nano-sized metastable precipitates within the aluminum matrix during the aging treatment [8][9][10][11][12][13]. These precipitates possess diverse atomic structures, resulting in variations in mechanical characteristics.…”

Electrochemical corrosion performance of Si-doped Al-based automotive alloy in 0.1 M NaCl solution

“…Automotive industry focus on lightweight materials like aluminium-silicon alloys for manufacturing automotive components like engine blocks, cylinder heads, pistons, intake manifolds and other parts, replacing steel and cast iron [1][2][3]. These lightweight materials not only increase fuel efficiency but also enhance properties such as high elongation values, high strength-to-weight ratio, and excellent corrosion resistance [4,5].…”

Wear studies on Al-Si automotive alloy under dry, fresh and used engine oil sliding environments

“…Aluminum alloys are widely used in transportation and other industries because they offer different useful properties like improved wear and corrosion resistance, good castability and a better combination of mechanical properties [1][2][3]. Among the various cast aluminum alloys known, Al-Si alloys have been well considered for these applications, mainly in automobile industries, e.g.…”