Formation of hydrogen blisters during the solution treatment for aluminum alloys

Abstract

The solution treatment of aluminum alloys can be restricted by the presence of porosity defects caused by the moisture present in the process or by the hydrated front on the material surface. Hydrogen blisters cause deleterious effects on mechanical properties and surface finish. However, the formation of bubbles in solid aluminum is not caused only by the known reaction 2Al+3H 2 O=3H 2 +Al 2 O 3 , as it does not explain the interaction of the aluminum oxide layer with the formation mechanisms. In addition, the literature approaches show that there is more than one mechanism for the formation of these defects, but no work has made an association between them. Thus, the objective of this work is to carry out extensive research on the state of the art of hydrogen blister formation in aluminum alloys during the solubilization heat treatment. Contemplating different proposed mechanisms of bubble formation on the surface and structure, the analysis of this association of approaches indicated that the mechanisms depend on both permeability, where the hydrated oxide front creates passage for the formation of blister in the sublayer, as well as diffusion and hydrogen solubility in the microstructure.

Universal Flexible Lamination Encapsulation Strategy toward Underwater-Operation Electroluminescence Devices

“…It was found that the content of the oxygen element in the crater area increased significantly, indicating the high probability of aluminum oxidation in these areas. Therefore, we speculate that when the device is operated or stored in water, the aluminum electrode would react with the water molecules invading the device under the boost of Joule heat, producing hydrogen gas and alumina according to the equation: 2Al + 3H 2 O → 3H 2 + 2Al 3+ + 3O 2– → 3H 2 + Al 2 O 3 . − The resulted alumina would reduce the conductivity of the Al electrode due to its insulating nature, consistent with the color change from bright to dark in the SEM image of the Al electrode (Figure b). Furthermore, the continuous formation of hydrogen gas might cause high pressure inside the devices, with the potential for damaging expansion and even destruction of the encapsulating barrier, further accelerating the device failure.…”

Microstructure, Mechanical Properties, and Thermal Stability of Al-Al2O3 Nanocomposites Consolidated by ECAP or SPS from Milled Powders

“…The release of these gases might also partly explain the cracking issues encountered during ECAP-HT. Several examples of «hydrogen blisters» (that is: near-surface cracks due to trapped hydrogen) in conventional Al alloys formed during casting or heat treatments [49][50][51] can be found in the literature.…”

Use of High-Pressure Heat Treatment (HPHTTM) for L-PBF F357

“…A method commonly used to minimize or eliminate such defects is hot isostatic pressing (HIP). However it has been reported in literature that hydrogen porosity and blistering is a common issue in aluminum castings and L-PBF components [5,6,7]. The hydrogen porosity and blistering present in castings can be managed with appropriate melt strategies.…”