An XPS analysis of the oxide surface layers formed on a friction stir processed magnesium alloy

作者：Cristobal M J; Gesto D; Minino P; Pena G^*; Rey P; Verdera D

来源：Surface and Interface Analysis, 2012, 44(8): 1030-1034.

DOI：10.1002/sia.4859

• Mg alloys
• AZ31
• FSP
• XPS
• surface oxide

Friction stir processing (FSP) is a promising technique for improving plasticity of magnesium alloys through the homogenization and grain refinement of their structure. In this study, a magnesium alloy AZ31 has been processed by FSP to achieve an ultrafine grain size structure (700?nm), and the oxide films formed spontaneously on the surface of the FSP zone are compared with those on the unprocessed material. Chemical composition of the oxide films are analyzed by XPS. The natural oxide films, close to 36?nm, can be described as a structure of (MgO)/Mg(OH)2 with the outermost surface mainly formed by Mg(OH)2/MgCO3. About 5-7?at.% of Al3+ is distributed through the oxide layer. Segregated zinc enrichment (Zn 2p3/2 at 1021.4 eV) at the interface oxide/metal is found. The FSP samples show higher carbonatation degree at the surface and a lower segregated zinc percentage at the interface oxide/metal.

• 出版日期2012-8