No abrupt reaction was observed during mechanical alloying (MA) of Ru and A
t powder mixtures with an eutectic composition (Ru70Al30). As-milled powder
s constitute mainly a Ru(Al) solid solution and/or mixture (matrix), and a
very small quantity of RuAl. The complete reaction between Ru and At during
MA was speculated to be hampered by excess Ru in Ru60Al30. No exothermic h
eat release was detected in differential scanning calorimetry for as-milled
powders. Precipitation of RuAl from as-milled Ru(Al) matrix was observed a
fter annealing at various temperatures. The phase fraction of Ru and RuAl r
eaches art approximately equilibrium value after annealing at 1173 K.