Fig.1 Microstructure images of the as-received and aged samples: a as-received, b 1000 h, c 1500 h, d 3000 h, e 5000 h, and f 8000 h

Fig.2 Grain size evolution

Fig.3 TEM images of the as-received and aged samples: a as-received, b 1500 h, c 5000 h, and d 8000 h

Fig.4 Misorientation angle distributions in the samples

Fig.5 BSE images of the as-received and aged steels: a as-received, b 1000 h, c 1500 h, d 3000 h, e 5000 h, and f 8000 h

Fig.6 Physical properties of the Laves phase precipitates in the alloy: a mean spatial diameter, b number of particles per unit volume, and c volume fraction

Fig.7 Evaluation of the time exponent (n) based on the physical properties of the Laves phase precipitates

Fig.8 TEM micrographs (a, b) and EDS results (c and d) of the M23C6 carbides in the as-received alloy (a, c) and sample that was thermally aged for 8000 h (b, d)

Fig.9 Orowan yield stresses of the M23C6 carbides (black) and the Laves phase precipitates (red) with thermal aging time

Fig.10 TEM micrographs (a, b) and EDS results (c, d) of the samples that were thermally aged for 1500 h (a, b) and 8000 h (c, d)

Fig.11 TEM images (a-d) and EDS results (e, f) of the MX carbides in the as-received and thermally aged samples: as-received (a, e), 3000 h (b), 5000 h (c, f), and 8000 h (d)

Fig.12 Effect of thermal aging on alloy hardness

Fig.13 Effect of thermal aging on alloy strength

Fig.14 Impact curves of the as-received and thermally aged samples