Pressure-enhanced thermal stability against eutectic crystallization in Al-based metallic glasses

Consolidation of mechanically alloyed Mg49Y15Cu36 powders by vacuum hot pressing

“…This means the second effect of suppression of atomic mobility at higher pressures becomes dominating factor, thus the amount of amorphous phase in the hot-pressed samples increases with increasing pressure. Similar results have also been found in Al 84 Ni 10 Ce 6 , Al 82.5 Ni 5 Y 8 Co 2 Zr 2.5 [11] and Zr 55 Al 10 Ni 5 Cu 30 [12] BMGs.…”

Correlation between heat- and deformation-induced crystallization of amorphous Al alloys

“…Consequently, applied pressure decreases the nucleation work, and thus the crystallization temperature decreases with pressure in the former alloys while the opposite behavior occurs in the latter. This result was corroborated by other works [26][27][28][29][30] for distinct Al-rich and TM-or RE-richer alloys.…”

“…Ye and Lu [25] showed that, in alloys that undergo primary crystallization, T x decreases with increasing pressure and that the opposite behavior occurs in alloys that undergo eutectic-like crystallization. Considering (i) that the density of an amorphous phase is often a few percentage points lower than its corresponding crystalline phase, (ii) that the amorphous/crystalline interface has a lower coordination than both the crystalline and amorphous phases, and (iii) that the interface formation involves a positive volume change [26], Ye and Lu explained their result based on the volume change that occurs in the formation of a critical nucleus during the crystallization process: it is negative for alloys that undergo primary crystallization and positive for alloys that undergo eutectic-like crystallization. Consequently, applied pressure decreases the nucleation work, and thus the crystallization temperature decreases with pressure in the former alloys while the opposite behavior occurs in the latter.…”

Devitrification of Al-based glass forming alloys

“…These results confirm the absence of any crystalline phase except the Al-nanocrystals at temperatures below the sharp crystallization signal at 374 • C that corresponds to the formation of the Al 3 Y-type intermetallic phase ( Fig. 3f) [6]. TEM investigations on annealed samples have shown that ␣-Al nanocrystals can slowly grow at temperatures well below the primary crystallization onset temperature.…”