Deformation of Ru–Al–Ta ternary alloys

The microstructure, flow behavior and dislocation substructure in two ternary ruthenium-containing alloys, Ru25Al25Ta (atomic percent) and Ru32Al13Ta were studied. The Ru25Al25Ta alloy consisted of a continuous Heusler phase with a small volume fraction of Ru-rich precipitates, while the Ru32Al13Ta contained a single phase B2 structure. Ru25Al25Ta failed in compression before yielding at both 298 and 973 K. Ru32Al13Ta exhibited limited compressive ductility (∼5%) at room temperature. The 2% flow stress decreased with temperature, but remained as high as about 1140 MPa at 1173 K. Dislocation substructures in Ru32Al13Ta following deformation at 298 and 973 K were similar in that the majority of the dislocations were the 〈111〉 type in bowed-out configurations on {110} planes. The 〈111〉 dislocations also contained periodic cusps along their length. The deformation behavior of the two alloys is discussed in relation to other RuAl-based alloys and possible implications for the dominant presence of 〈111〉 dislocations are presented.