Effect of Ag or Pd additions on the microstructure, crystallization and thermal stability of Al-Ni-Ce amorphous alloys

摘要

Effect of Ag or Pd additions on the microstructure, crystallization and thermal stability of Al_(85)Ni_(10)Ce_5 amorphous alloys has been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and differential scanning calorimetry (DSC). The results show that there are quenched-in nuclei in the Ag or Pd doped Al-Ni-Ce amorphous alloys, resulting in the formation of a shoulder peak on the XRD patterns. Moreover, the Pd doped Al-Ni-Ce amorphous alloys contain more and larger quenched-in nuclei than the Ag doped alloys. The Ag addition decreases the crystallization onset temperature, activation energy and thermal stability of the Al-N-Ce amorphous alloys, while the Pd addition greatly improves the crystallization onset temperature, activation energy and thermal stability of the amorphous alloys. The influence of the Ag or Pd additions on the crystallization and thermal stability of the Al-Ni-Ce amorphous alloys has been discussed based upon the existence of pre-existing quenched-in nuclei, chemical affinity between Al and additional elements, and diffusion of atoms.