Behavior of Hydrogen in a Tensile-Deformed Al-Mg Alloy

Abstract

Behavior of hydrogen in a tensile deformed Al 9 massMg alloy was investigated by means of hydrogen microprint technique, HMPT, a method to visualize the microscopic location of hydrogen emission from specimen surface as silver particles. Hydrogen emission was observed on some of grain boundaries. The amount of surface relief and the maximum gradient across the grain boundary with hydrogen emission were larger than those without hydrogen emission. Most grain boundaries with hydrogen emission were from 61 to 75 degree to tensile direction and nearly parallel to slip lines. The results suggest that slip deformation parallel to and close to grain boundary plane caused hydrogen transport with moving dislocations to the surface, breakage of the surface oxide film on the grain boundary, and then the emission of the hydrogen atoms.

Behavior of Hydrogen in Tensile-Deformed Aluminum Alloys

“…The height of surface relief of grain boundaries with hydrogen evolution was relatively larger than those without hydrogen evolution [4]. Also, the maximum gradient of the surface relief was nearly 45 degrees in both alloys [4,5]. These results indicate that plastic deformation near grain boundary was deduced to play a great role in the hydrogen emission rather than the misorientation between the two neighboring grains.…”

“…Figure 2 shows HMPT/SEM images of tensile-deformed Al-Mg alloy [4]. A number of white particles were observed at some grain boundaries and slip lines of each specimen.…”

“…Most grain boundaries with hydrogen evolution are from 61 to 75 degrees in the Al-Mg alloy, while from 46 to 60 degrees in the Al-Zn-Mg alloy, and nearly parallel to slip lines in the two alloys. The height of surface relief of grain boundaries with hydrogen evolution was relatively larger than those without hydrogen evolution [4]. Also, the maximum gradient of the surface relief was nearly 45 degrees in both alloys [4,5].…”

“…These results indicate that plastic deformation near grain boundary was deduced to play a great role in the hydrogen emission rather than the misorientation between the two neighboring grains. We proposed the mechanism of hydrogen evolution from grain boundary as follows: the shear deformation along and close to grain boundary plane caused transportation of hydrogen atoms with gliding dislocations to the surface, breakage of surface oxide film, formation of surface relief and then emission of hydrogen atoms [4,5].…”

“…The authors have investigated the behavior of hydrogen in tensile-deformed aluminum alloys using HMPT [4,5]. In this paper, the mechanism of hydrogen evolution from grain boundary in Al-Mg and Al-Zn-Mg alloys will be described.…”