Microstructure and Corrosion Characteristics According to the Si Content of Al–Ca-Si Alloys

Abstract

Aluminum is a general-purpose metal widely used in industrial fields owing to its excellent characteristics such as high specific strength, low density, excellent formability, and adequate corrosion resistance. However, Al has poor mechanical properties. To address this limitation, trace elements such as Si, Mg, and Cu are added to form Al alloys; however, the corrosion resistance is often reduced. Therefore, the development of an Al alloy that exhibits satisfactory mechanical properties, castability, and corrosion resistance is necessary. To this end, Al–Ca-based alloys were developed. The microstructures of these alloys were analyzed, and results indicated the formation of Al4Ca+Al2Si2Ca with a fine lamellar structure. The alloys in which Si was added to the Al–Ca-based alloy had more refined structures. Moreover, AC4S7 exhibited a fine microstructure, formed a highdensity shallow pit, and served as a barrier to corrosion products, which is a major advantage. Electrochemical measurements were conducted, which demonstrated the positive influence of this structure in improving the corrosion resistance of the alloy.