Figure 2
3D reconstructions of (a)–(e) Al–Co–Ni d-QC growth, and (f)–(j) its dissolution (in green), followed by (k)–(t) X-phase crystallization (in red) during continuous cooling (1 K min−1). The z axis in the specimen frame points along the rotation axis of our cylinder sample. Temperatures and times are as follows: (a) 1259.8 K (800 s), (b) 1259.2 K (840 s), (c) 1257.2 K (960 s), (d) 1253.2 K (1200 s), (e) 1247.8 K (1520 s), (f) 1243.5 K (1780 s), (g) 1238.5 K (2080 s), (h) 1235.2 K (2280 s), (i) 1233.8 K (2360 s), (j) 1233.8 to 1227.2 K (2360 to 2760 s), (k) 1227.2 K (2760 s), (l) 1226.8 K (2780 s), (m) 1226.5 K (2800 s), (n) 1226.2 K (2820 s), (o) 1225.8 K (2840 s), (p) 1224.5 K (2920 s), (q) 1220.8 K (3140 s), (r) 1218. 8 K (3260 s), (s) 1217. 8 K (3320 s) and (t) 1215.5 K (3460 s). The times given in parentheses are with respect to the start of the XRT experiment at 1273.2 K (0 s). A thin grey layer indicates the Al2O3 protective skin of the molten alloy sample that was grown naturally by thermal oxidation. We observe the nucleation and growth of a single d-QC at high temperatures and multiple X-phase crystals at lower temperatures (see Section 3.1). |