Microstructure and internal friction of spray deposited Al-3.3Fe-10.7Si alloy

Al-3.3Fe-10.7Si alloy has been experimentally made with spray deposition te chnology. The internal friction of the alloy which was directly associated with the microstructures under spray deposited, extruted and heat treated c onditions has been investigated using a low frequency inverted torsion pend ulum over the temperature region of 10-300 degrees C. An internal friction peak was observed in the temperature range 50-250 degrees C in the present alloy. The Q(-1) peak decreased after extruted and in subsequent to the ear liness of isothermal annealing, which was found to be directly attributed t o the precipitation of FeAl2 and Al-Fe-Si intermetallics from the supersatu rated aluminium alloy matrix. We suggest that the internal friction peak in the alloy originates from grain boundary relaxation, but the grain boundar y relaxation can also be affected by FeAl2 and Al-Fe-Si intermetallics at t he grain boundaries, which will impede grain boundary sliding. (C) 2000 Klu wer Academic Publishers.