MICROSTRUCTURE AND STRENGTH OF BINARY AND TANTALUM ALLOYED 2-PHASE NB-SS NB3AL BASE ALLOYS/

Niobium aluminide (Nb3Al) base intermetallic compounds are potential c andidates for applications at temperatures above the operating tempera tures of currently used superalloys, provided their low-temperature du ctility and fracture toughness and high-temperature oxidation resistan ce are improved. Two-phase (Nb-55/Nb3Al) materials with different volu me fractions depending on the aluminium content were prepared by ingot metallurgy followed by isothermal forging and heat treatment. The add ition of tantalum (about 10 mol%) has no influence on the phase conten t: volume fraction and grain size: The compressive strength of both th e binary and ternary alloys investigated depends strongly on the alumi nium content. increasing the volume fraction of Nb-55 phase decreases the strength at all temperatures tested. The addition of tantalum impr oves the high-temperature strength of Nb-55/Nb3Al alloys.