From measurements on more than two hundred alloys four binary intermetallic compounds have been identified that melt above 1900°C and are tough at ambient temperature. Effects of alloying on elastic properties and room-temperature toughness are given for two of these compounds, RuTa (an L1₀(tP4) structure) and AIRu (a B2(cP2) structure). For selected alloys other mechanical data are presented. The high-temperature hardness of AIRu alloys are improved by 4%Sc, 0.5%B doubles the compressional strain to fracture, and Cr aids the oxidation resistance.