Study on the microstructure and corrosion behavior of Mg–(4 − x)Gd–xY–2Zn (x = 0, 2, 4 wt%) alloy

Abstract

The relationship between the corrosion behavior of Mg–Gd–Y–Zn alloy and the content of rare earth elements was investigated. The results show that the Mg–4Gd–2Zn (VZ42) contains only α‐Mg matrix and W phase, while there are α‐Mg matrix, W phase and X phase in Mg–2Gd–2Y–2Zn (VWZ) and Mg–4Y–2Zn (WZ42). The corrosion rates measured by weight loss of VZ42, VWZ, and WZ42 are 8.17, 4.49, and 6.05 mm/year, respectively. Through the observation of microstructure, it is found that the corrosion first occurs around the W phase, which means that the micro galvanic effect caused by the W phase is more serious than that of the X phase. The more W phase, the greater the corrosion rate of the alloy. But continuously distributed layered X phase will form a barrier and protect α‐Mg from corrosion. It is found that different distribution of the second phase will also lead to different corrosion resistance.