Stability of supersaturated solid solution of aluminum alloy 1450

Decomposition of the solid solution in commercial semiproducts from aluminum alloys

“…However, this phenomenon has not been explained. Later we confirmed this fact when we plotted thermokinetic diagrams for alloy 1420 [9] and then for other A1 -Li alloys [12,14]. We also established the cause of the segregation of 8'-phase, namely, the fact that the lower branch of the C-curve is shifted more to the left of the time axis for all AI -Li alloys in the low-temperature range relative to alloy D16.…”

“…This concept agrees well with the data of differential scanning calorimetry (DSC) of aluminum alloys. The scheme (succession) of the decomposition of the solid solution presented in [16] is implementable under industrial conditions, has been confirmed by the results of transmission electron microscopy, x-ray phase analysis, and differential scanning calorimetry, and agrees well with the thermokinetic diagrams [9,12,13,16,17]. The presented series of phase transformations are realized in actual heat treatment of a wide range of commercial stamped preforms from alloy 1420.…”

“…By changing the heat treatment regimes we can suppress as desired the segregation of the typical phases or, on the contrary, cause the formation of atypical (from the standpoint of standard heat treatment regimes [9,13]) phases. For this purpose we should study the thermokinetic C-diagrams.…”

“…We have devoted some works to studying the stability of the solid solution under the conditions of continuous cooling of A1-Li alloys (1420 [9], 1421 [12], 1450 [13], and 1470 [14]) and proved this concept. This allows me to make the following conclusions:…”

Delayed fracture of aluminum alloys

“…[8,17] in a water-air mixture (in the center of a sheet 2 mm thick Vcool = 1.5 and 12 K/sec, respectively).…”