Synthesis of nanocrystalline B2 structured (Ru, Ir) Al in the ternary Ru-Al-Ir system by mechanical alloying and its thermal stability

B2 structured single-phase (Ru,Ir)Al is synthesized directly in the ternary Ru-Al-Ir system by mechanical alloying. Complete solubility between pseudo -binary RuAl-IrAl is achieved in a composition range 10-25 at.% Ir, while t he range for Al remains at 50 at.%. B2 structured (Ru, Ir) Al is formed by an abrupt reaction at the beginning of milling of all three compositions an d a certain quantity of Ir was found to remain after the reaction. Further alloying and a reaction between It and sticking Al on the surfaces of milli ng tools take a much longer time and finally result in single-phase B2 stru ctured (Ru, Ir) Al. The ternary alloying element It has been found to ameli orate the sluggish reactivity of Ru by promoting the abrupt reaction. No de composition process has been observed for the as-milled single-phase (Ru, I r) Al by means of high-temperature X-ray diffraction, demonstrating the com plete mutual solubility between pseudo-binary RuAl and IrAl in the present composition range. The structural evolution of as-milled materials includes reordering, strain relaxation and grain growth. The grain size of the as-m illed (Ru, Ir) Al after exposure to elevated temperatures (up to 1273 K), t urns out to be less than 30 nm and reflects its strong thermal stability.