Coarsening of Al3Sc precipitates in Al-Mg-Sc alloys

The coarsening characteristics of Al3Sc precipitates in Al-5Mg-0.3Sc (in wt.%) alloys annealed at 300 -450 degrees C were studied using transmission electron microscope (TEM), with the annealing temperature of the alloy found to have a significant influence on its coarsening rate. Increasing the temperature range from 300 to 450 degrees C resulted in the coarsening rate increasing by an order of magnitude for every 50 degrees C. Experimental precipitation results were well correlated with theoretical results produced using a KV model. The diffusion activation energy of the Al3Sc precipitates was shown to be around 189 +/- 8 kJ mol(-1), with the precipitates exhibiting good coherency with the aluminum matrix, even after being annealed at 300-450 degrees C for 168 h. (C) 2018 Elsevier B.V. All rights reserved.