TAKESHI NAGASE, TAKASHI HOSOKAWA, and YUKICHI UMAKOSHI Both amorphization and crystallization were observed in Zr 66.7 Pd 33.3 metallic glass under electron irradiation. The melt-spun amorphous phase was not stable under 2.0 MV electron irradiation and two kinds of fcc-solid solution were precipitated through electron irradiationinduced crystallization at 103 and 298 K. The fcc-solid solution obtained by electron irradiation-induced crystallization at 298 K transformed to an amorphous phase during irradiation at 103 K. Electron irradiation-induced phase transformation behavior in Zr 66.7 Pd 33.3 metallic glass can be explained by phase stability of an amorphous phase and crystalline phases against electron irradiation.