Bimodal Microstructure Obtained by Rapid Solidification to Improve the Mechanical and Corrosion Properties of Aluminum Alloys at Elevated Temperature

Abstract

The demand for aluminum alloys is increasing, as are the demands for higher strength, with the aim of using lighter products for a greener environment. To achieve high-strength, corrosion-resistant aluminum alloys, the melt is rapidly solidified using the melt-spinning technique to form ribbons, which are then plastically consolidated by extrusion at elevated temperature. Different chemical compositions, based on adding the transition-metal elements Mn and Fe, were employed to remain within the limits of the standard chemical composition of the AA5083 alloy. The samples were systematically studied using light microscopy, scanning electron, and transmission microscopy with electron diffraction spectrometry for the micro-chemical analyses. Tensile tests and Vickers microhardness were applied for mechanical analyses, and corrosion tests were performed in a comparison with the standard alloy. The tensile strength was improved by 65%, the yield strength by 45% and elongation by 14%. The mechanism by which we achieved the better mechanical and corrosion properties is explained.

Microstructure and Mechanical Properties of Al-Si Alloys Produced by Rapid Solidification and Hot Extrusion

“…From the air side, a typical dendritic structure can be seen, which indicates a slower heat dissipation from this side. Similar results can be found in the literature [22,31] In addition, from the observation of the microstructures of the strips, it can be seen that, depending on the amount of silicon, the zones of orthogonally growing crystals have different sizes. In the case of the AlSi5 RS material, this zone was 20 µm; for the AlSi11 RS material, it was 11 µm; and in the case of the AlSi20 RS material, this zone was only 6 µm.…”

“…The melt spinning method can be used to obtain high-strength, corrosion-resistant aluminum alloys. The use of this method in the case of AA 5083 alloy resulted in an increase in the tensile strength by 65%, the yield strength by 45%, and the elongation by 14% [22]. The RS process leads to the grain refinement of various materials.…”

Heterogenous Grain Nucleation in Al-Si Alloys: Types of Nucleant Inoculation

“…Aluminum owes this place to a set of properties which, in many circumstances, make it an irreplaceable material. During their use, metals change from a liquid to a solid state [1][2][3][4][5][6]. Additionally, the solidification of any metal or alloy can be studied by thermal analysis.…”

“…Identifying the effect of the interaction between the Sr modifier and the grain refiner (Al-10Ti, Al-5Ti-1B, and Al-4B), the interaction between silicon and titanium, and their competition in affecting the morphology of the eutectic silicon, on the grain size, and on the shape of the α-Al dendritic phase. 4.…”