| An investigation has been carried out for the influences of combined addition of Si, Fe, Mn and Ti on ageprecipitation in compulsive solid solution of Al-2.62wt%Cu-0.42 wt% Mg alloy by the observation of the transmission electron microscopy and the detailed measurement of specific heat and electrical resistivity during ageing at temperatura range between 150℃ and 300℃. The results obtained are summarized as follows. (1) The formation rate of pre-precipitation zones, G. P. B., has been accelerated slightly by the combined addition of Si, Fe, Mn and Ti. This result may be attributed mainly to the effects of Mn and Ti upon the nucleations of G.P.B. zones formation. (2) The nucleation and growth of the S` precipitates on and around the dislocations have been retarded pronouncedly by the combined addition. These results produced the more coarser distributions of S` precipitates in addition elements free alloy than those in addition elements combined alloy. (3) The major effects of combined addition of Si, Fe, Mn and Ti have been resulted more pronouncedly on the nucleation and growth of the S` precipitates than on the formation of the G. P. B. zones. These effects were presented more at the higher ageing temperatures. (4) Reversion temperature of G. P. B zones has been dropped down about 8℃ by the combined addition of Si, Fe, Mn and Ti. This result showed that the growth of G. P. B. zones are modified slightly by the combined addition. |
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