Fig. 5: Surface morphology of samples after DL-EPR tests.

BSE-SEM images of the solution-treated sample (a) and samples aged at 700 and 800 °C for 0.5 h (b, c), 1 h (d, e), 2 h (f, g), 4 h (h, i), 6 h (j, k), 8 h (l, m), and 10 h (n, o), respectively.