Artículos de revistas
On the thermal stability of ultrafine-grained Al stabilized by in-situ amorphous Al2O3 network
Fecha
2015-11Registro en:
Balog, Martin; Hu, Tao; Krizik, Peter; Castro Riglos, Maria Victoria; Saller, Brandon D.; et al.; On the thermal stability of ultrafine-grained Al stabilized by in-situ amorphous Al2O3 network; Elsevier Science Sa; Materials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing; 648; 11-2015; 61-71
0921-5093
CONICET Digital
CONICET
Autor
Balog, Martin
Hu, Tao
Krizik, Peter
Castro Riglos, Maria Victoria
Saller, Brandon D.
Yang, Hanry
Schoenung, Julie M.
Lavernia, Enrique J.
Resumen
Bulk Al materials with average grain sizes of 0.47 and 2.4μm, were fabricated by quasi-isostatic forging consolidation of two types of Al powders with average particle sizes of 1.3 and 8.9μm, respectively. By utilizing the native amorphous Al2O3 (am-Al2O3) film on the Al powders surfaces, a continuous, ~7nm thick, am-Al2O3 network was formed in situ in the Al specimens. Systematic investigation of the changes to the am-Al2O3 network embedded in the Al matrix upon heating and annealing up to 600°C was performed by transmission electron microscopy (TEM). At the same time, the stability of the Al grain structure was studied by transmission Kikuchi diffraction (TKD), electron back-scatter diffraction (EBSD), and TEM. The am-Al2O3 network remained stable after annealing at 400°C for 24h. In-situ TEM studies revealed that at temperatures ≥450°C, phase transformation of the am-Al2O3 network to crystalline γ-Al2O3 particles occurred. After annealing at 600°C for 24h the transformation was completed, whereby only nanometric γ-Al2O3 particles with an average size of 28nm resided on the high angle grain boundaries of Al. Due to the pinning effect of γ-Al2O3, the Al grain and subgrain structures remained unchanged during annealing up to 600°C for 24h. The effect of the am-Al2O3→γ-Al2O3 transformation on the mechanical properties of ultrafine- and fine-grained Al is discussed from the standpoint of the underlying mechanisms.