Effect of cerium addition on microstructure and corrosion resistance of die cast AZ91 magnesium alloy

Abstract

A novel AZ91 Ce containing magnesium alloy characterized by excellent corrosion resistance is fabricated by adding rare earth Ce (cerium) in the form of a Mg-Ce master alloy. The metallographic investigation shows that Ce added to AZ91 can obviously decrease the size of b-Mg 17 Al 12 and forms Al 11 Ce 3 intermetallic compounds in the shape of fine needles. The corrosion tests and electrochemical measurements indicate that the corrosion resistance of AZ91 Ce containing magnesium alloy is obviously higher than that of AZ91. Furthermore, increasing the content of Ce in the magnesium alloy can further enhance the corrosion resistance. X-ray photoelectron spectroscopy (XPS) reveals that Ce can be incorporated into corrosion products in the form of CeO 2 in the course of corrosion. Based on the preliminary analysis, the addition of Ce can improve the corrosion resistance of AZ91 by decreasing the size of bMg 17 Al 12 and enhancing the protective effectiveness of corrosion products.

Nano-ZnO Particles’ Effect in Improving the Mechanical Response of Mg-3Al-0.4Ce Alloy

“…While this could be either the Al11Ce3 phase or (Al,Mg)2Ce phase, previous research has shown that Al11Ce3 phase has a needle-like structure [9] and is the more dominant phase compared to (Al,Mg)2Ce [10]. Furthermore, XRD results also suggests that more peaks were observed for Al11Ce3 phase.…”

Effect of yttrium-rich misch metal on the microstructures, mechanical properties and corrosion behavior of die cast AZ91 alloy

“…Previous investigations [8][9][10] have validated that ␤ phase distributed along ␣ grain boundary could act as a micro-galvanic cathode considering the potential difference between ␣ and ␤ phase. The micro-galvanic-current between ␤ phase and adjacent ␣ grain preferentially brings on the corrosion of ␣ grain, and the ␤ Fig.…”

“…phase was finally undermined and flaked away. However, the devastation of micro-galvanic-corrosion will be weakened if ␣ grain and ␤ phase are refined [10]. Moreover, solid solution of aluminum in ␣ phase is beneficial to the corrosion resistance of ␣ phase [8,9].…”

“…12(a) and (b) shows the surface features of the corrosion area of AZ91 and AZ91-0.8Ymm alloys after 5 days corrosion tests. Taking into account the microstructure of AZ91 alloy in this work and the previous studies [8][9][10]18], as shown in Fig. 12(a), corrosion mainly originated in the interior of ␣ grain and the ␤ secondary phase was normally inert and stable.…”

“…However, its application is still limited to some components served in mild environments. In order to meet the challenges of new applications, mechanical properties and corrosion performance of AZ91 alloy need to be further improved urgently [6][7][8][9][10]. Some have reported that the addition of Ca, Sr, Si, Sb or rare earth elements is the effective way to improve the performance of AZ91 alloy [5,[10][11][12][13][14][15][16][17].…”