X-ray microanalysis for studying the corrosion processes

X-ray microanalysis has been applied to study the intergranular corrosion processes in Fe-Cr-Mn, Al-Cu, and Fe-Zn alloys, as follow: (1) The phase, deposited on the crystal grain boundaries during annealing of Fe-Cr-Mn alloy, which causes a disposition to intergranular corrosion, has been investigated. It is experimentally shown that the carbon and chromium concentrations in the deposits increase, and those of the iron and manganese decrease as compared to the matrix composition. Analogically, Al-Cu alloy has been studied and the intermetallic compound CuAl2 on the grain boundaries quantitatively determined. (2) The high temperature oxidation of the binary alloy system Fe-Zn has been studied. Alloy component concentration changes in the oxide and suboxide layer are registered. Internal oxidation is also observed. (3) The corrosion of Fe-Zn alloy in alkaline chloride melt has been studied. A decrease in the zinc content on the grain boundaries and in the grain volume is observed. (N.K.)