Thermal studies on high temperature oxidation behaviour of nickel containing AB<inf>5</inf> type intermetallics

The oxidation behaviour of nickel containing AB5 type intermetallic compounds LaNi5 and CaNi5 has been studied in an oxygen atmosphere by thermogravimetric (TG) and differential thermal analysis (DTA). The TG of LaNi5 showed complete oxidation of lanthanum and nickel whereas that of CaNi5 showed partial oxidation. The DTA curve of LaNi5 showed four irreversible peaks, which have been attributed to the formation of La2O3, NiO and ternary oxides. However, the DTA pattern of CaNi5 did not show any maxima, indicating slow oxidation of CaNi5. The difference in the oxidation behaviour has been explained on the basis of the formation of ternary oxides and the heat of reaction. © 1990.