The oxidation behavior of 60%Cu-40%Zn brass having small amounts of Zr, Cr, Mg, Al, and Si was studied between 873 and 1043 K in air. The alloying element of Mg was harmful, while other alloying elements were beneficial to oxidation resistance. Particularly, the simultaneous addition of Al and Si decreased the oxidation rate drastically. During oxidation, Zr formed ZrO 2 , Cr formed CuCr 2 O 4 , Mg formed MgO, Al formed Al 2 CuO 4 , and Si formed amorphous SiO 2 . These oxides were incorporated in the oxide scale composed predominantly of ZnO. The oxide scales formed on all the tested alloys were prone to cracking, wrinkling, and spallation.

Chromium nitride powders oxidized to Cr 2 O 3 noticeably above 400 o C. Bulk chromium nitrides that were manufactured by sintering were oxidized between 900 and 1100 o C in atmospheric air. The Cr 2 O 3 layer that formed on bulk chromium nitrides having pores was relatively dense, and grew primarily via the inward transport of oxygen. The Cr 2 O 3 layer to some degree deterred the nitrogen evolution from bulk chromium nitrides.

TiAl alloys incorporated in (0,3,5,10) wt.% TiB 2 dispersoids were manufactured via mechanical alloyingspark plasma sintering (MA-SPS), and their cyclic oxidation characteristics were studied at 800, 900 and 1000 o C in air. The cyclic oxidation resistance of the prepared TiAl-TiB 2 composites effectively increased with increases in TiB 2 content. The oxide scale formed consisted of an outer TiO 2 layer, an intermediate Al 2 O 3 layer, and an inner (Al 2 O 3 +TiO 2 ) mixed layer. The scale adherence was relatively good, and much thinner oxide scales, when compared to TiB 2 -free TiAl alloys, were formed on the prepared composites. The incorporated TiB 2 dispersoids oxidized to TiO 2 and B 2 O 3 which evaporated during oxidation.

No abstract