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

Abstract

The paper presents the results of tests of rapid solidification (RS) aluminum alloys with the addition of silicon (5%, 11%, and 20%). Casting by melt-spinning on the surface of an intensively cooled copper cylinder allowed to obtain a metallic material in the form of flakes, which were then consolidated in the process of pressing and direct extrusion. The effect of refinement on structural components after rapid solidification was determined. Rapidly solidified AlSi materials are characterized by a comparable size of Si particles, regardless of the silicon content, and the shape of these particles is close to spheroidal. Not only Si particles are fragmented, but also the Al-Si-Fe phase, which also changed its shape from irregular with sharp edges to regular and spherical. The melt-spinning process resulted in a fine-grained structure compared to materials obtained by gravity-casting and extrusion. The influence of the high-temperature compression test on the mechanical properties of rapidly solidified materials was analyzed, and the results were compared with those of gravity-cast materials. An increase in strength properties was found in the case of the AlSi5 RS alloy by 20%, in the case of AlSi11RS by 25%, and in the case of the alloy containing 20% Si by as much as 86% (tensile test). On the basis of the homogeneity of the particle distribution determined by the SEM method, it was found that rapid solidification is an effective method of increasing the strength properties and improving the plastic properties of Al-Si alloys.

Recycling of Hard Disk Drive Platters via Plastic Consolidation

“…The higher elongation in the case of plastically consolidated materials (curves B and C) compared to the gravity cast material (curve A) is caused by the presence of large areas of the plastic matrix, which can be seen in Figure 5. Similar research results can be found in the literature [36,52].…”

“…In the case of components such as chips, this is more problematic, due to the fact that after machining processes, chips are often contaminated with coolant and their surface oxidizes quickly, which causes a decrease in the efficiency of the melting process. Remelting the chip after the machining process, such as cutting, turning, or milling, is very unprofitable because, at the end of the process, we will have achieved only 40% of the input material mass, to obtain up to 100% of the mass of the finished product, compared to the mass of the input material [35,36].…”

Tool Run-Out in Micro-Milling: Development of an Analytical Model Based on Cutting Force Signal Analysis

“…The analysis also shows how higher values of Kts lead to lower values for the Equation (30) terms, as the influence of Kts on the model variables is reduced. In conclusion, the terms a•(rCE1) 4 , b•(rCE1) 3 , and e•(rCE1) are approximated to zero.…”

“…Aluminum alloys have broad potential for applications in aerospace, automotive, defense, electronics, and biomedical industries, but the performances of parts produced by the traditional casting process are poor [ 2 ]. Traditional casting and its low cooling rates cause macro-segregation and coarse structures in aluminum alloys [ 3 ]. To overcome this issue, together with the need for a long production chain and the limited flexibility of plastic processing, numerous studies on AM can be found in the literature.…”

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.…”