A composite material based on polyethylene terephthalate (PET, about 1% by mass) and Al85Y8Ni5Co2 metallic glass was obtained by mechanical alloying and consequent spark plasma sintering. The spark plasma sintering was performed at a temperature near to the super cooled liquid region of the metallic glass. Mechanical properties and the structural characterization of the composite material were obtained. It was conceived that composite samples (Al85Y8Ni5Co2/PET) have a better thermal conductivity in comparison with pure PET samples. The formation of the crystalline phases causes degradation of physical properties. It was calculated that the activation energy for crystallization of the Al85Ni5Y8Co2 metallic glass is higher than that of the other types of metallic glasses (Mg67.5Ca5Zn27.5 and Cu54Pd28P18) used for composite preparation previously. This denotes a good thermal stability of the chosen metallic glass.