抄録
A fluoride-treatment has been applied to various magnesium alloys, such as 3N-Mg, AZ31, AZ61, AZ91E and Ca-added AM60 alloys. The specimens of the alloys are dipped into molten NaBF4 at 673 to 723 K for 0.3 to 86.4 ks. Surfaces of the specimens were successfully coated with surface layer by the treatment. Diffraction measurement in the synchrotron radiation facility SPring-8, BL-24XU (Hyogo prefecture beam line) showed that the surface layer was composed of NaMgF3 and MgF2 phases. The surface fluoride layer exhibits a superior corrosion resistance even in an immersion test using a 1% HNO3 solution, filiform-like corrosion was suppressed for 1 to 3 ks in the solution depending on the alloy. Aluminum contents in the substrate alloys would affect the corrosion resistance by changing the microstructures in the fluoride layer.
