Interfacial reaction during the fabrication of Ni60Nb40 metallic glass particles-reinforced Al based MMCs
Ni60Nb40 metallic glass powders were prepared by mechanical alloying and subsequently combined with Al to form an Al–30 wt.% Ni60Nb40 metal matrix composite (MMC). The crystallization of the Ni60Nb40 metallic glass reinforcements and their reaction with the Al matrix during preparation of the MMC were investigated in a differential scanning calorimeter (DSC) upon isothermal annealing. The comparison of the DSC curves of the Ni60Nb40 metallic glass and of the Al–30 wt.% Ni60Nb40 composite shows that the amorphous Ni60Nb40 particles have a very strong resistance against reaction with Al but reaction occurs after crystallization of the metallic glass. The analysis of the isothermal annealing DSC curves gives an activation energy of crystallization of the Ni60Nb40 metallic glass of 724 kJ/mol. The interfacial reaction between Al and the Ni60Nb40 reinforcements is mainly controlled by diffusion. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicate that during the interfacial reaction, Ni diffuses from the Ni60Nb40 particles to react with Al and form Al3Ni. At the same time, Al diffuses into the reinforcement particles to react with remaining Nb and form Al3Nb.