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 °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 °C resulted in the coarsening rate increasing by an order of magnitude for every 50 °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 °C for 168 h. •The critical size for loss of coherency increased in the presence of Mg.•The coarsening rate of Al3Sc precipitates was measured.•The diffusion activation energy for Al3Sc precipitates was 189 ± 8 kJ mol−1.