Thermal expansion of a La-based bulk metallic glass: insight fromin situhigh-energy x-ray diffraction

Constant-rate heating experiments using a fast x-ray camera (time resolution of 2.7 s) reveal detailed information about the thermal stability of La 62 Al 14 (Cu 5/6 Ag 1/6 ) 14 Ni 5 Co 5 (at.%) bulk metallic glass.Analyzing diffraction patterns in reciprocal space yields the thermal expansion of the amorphous alloy providing insight about the thermally activated relaxation effects and kinetics of the glass transition.The glass transition appears as a break in the value of the coefficient of volume thermal expansion.Furthermore, real space analysis based on reduced pair distribution function G(r) allows one to follow in-situ the changes in the local atomic structure of the amorphous material during constant-rate heating.