Undercooling behavior of Zr–Cu–Ni–Al bulk metallic glasses investigated by in situ synchrotron high energy X-ray diffraction

Three quaternary Zr–Cu–Ni–Al bulk metallic glasses are undercooled via the containerless aerodynamic levitation technique and investigated by using in situ high energy X-ray diffraction. By tracing the temperature T dependent evolutions of the maximum diffraction peak position Qmax(T) and the integrated maximum diffraction peak intensity Imax(T), glass transition and/or crystallization is identified occurring at the temperature that corresponds to the slope change of the linear functions Qmax(T) and Imax(T). Glass transition temperature Tg, onset crystallization temperature Tx,c, critical cooling rate Rc, and the volumetric thermal expansion coefficient of the three alloy in liquid state αV,l are evaluated during melt cooling.