The effects of reducing the grain size by high-pressure torsion HPT on the pitting corrosion resistance of Al-Fe alloys with Fe contents of 0.5, 2, and 5mass% were investigated by means of polarization curves in solutions containing 0.1 mol-dm-3 Na2SO4 and 8.46 mmol-dm -3 NaCl (300 ppm Cl-) at 298 K and by surface analysis. The potentials for pitting corrosion of the Al-Fe alloys were clearly shifted to the noble direction by HPT, leading to an improvement in pitting corrosion resistance. This improvement was larger in the Al-0.5%Fe and Al-2%Fe alloys and smaller in the Al-5%Fe alloy. The Al-Fe alloys contained precipitates of Al-Fe intermetallic compounds, around which pitting corrosion occurred. The Al-5%Fe alloy, in particular, contained large precipitates tens of micrometers in size, and pitting corrosion was significant around these large precipitates. It is evident from the time-dependence of the corrosion potential and the polarization resistance of the corrosion reaction that the formation rate of AI oxide films increases as a result of HPT. It was therefore concluded that the improvement in pitting corrosion resistance ot the Al-Fe alloys with HPT is causea by increasing the oxidation rate of Al.
|ジャーナル||Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals|
|出版物ステータス||出版済み - 11 1 2013|
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys
- Materials Chemistry