Effect of rare earth addition on solidification characteristics and microstructure of ZRE1 magnesium cast alloy

Abstract

The thermal parameters of ZRE1 cast alloy with 1.0 wt.% of praseodymium (Pr) and 1.0 wt.% of erbium (Er) were evaluated by the computer-aided cooling curve thermal analysis (CA-CCTA), whereas the microstructure analysis was investigated by the optical microscope and field emission scanning electron microscopy. The results of the cooling curve and microstructure analyses showed that Pr and Er reduced the grain size. The thermal analysis result recorded a faster freezing time and lower solidification temperature with Pr and Er additions and 15.5 and 11.2% decrease in the grain size, respectively. Scanning electron microscopy results showed that Er formed a granular particles of Er-containing phases existed in the α-Mg matrix, while Pr formed Mg–Zn–Pr–Ce phase with secondary phase which distributed along the grain boundaries.