Formation and phase evolution of liquid phase-separated metallic glasses with double glass transition, crystallization and melting

Abstract Zr 57 Co 27 Al 16 and La 57 Co 27 Al 16 alloys with excellent glass-forming ability (GFA) were adopted to synthesize new phase-separated bulk metallic glasses (BMGs) upon rapid solidification. (Zr x La 1 − x ) 57 Co 27 Al 16 (x = 0.2, 0.4, 0.6, and 0.8) melts separate into ZrCo-rich and La-rich liquids upon cooling due to the existence of a miscibility gap in Zr-La liquids. The intrinsic and extrinsic mechanisms for the formation of phase-separated alloys under different casting conditions were analyzed in detail. The GFA of the studied alloys changes in the following order: Zr 57 Co 27 Al 16  > La 57 Co 27 Al 16  > Zr 11.4 La 45.6 Co 27 Al 16  > Zr 22.8 La 34.2 Co 27 Al 16  > Zr 34.2 La 22.8 Co 27 Al 16  > Zr 45.6 La 11.4 Co 27 Al 16 . The quaternary Zr-La-Co-Al phase-separated metallic glasses (MGs) are shown to experience double glass transition, crystallization and melting events, which could be regarded as possible model materials to study the glassy transition and structural relaxation behavior of BMGs.