Microstructure and high temperature compressive strength of Nb-Ir alloys

Mechanical behavior of binary Nb-Ir alloys was investigated by compression tests at the temperatures ranging from room temperature to 1773 K. It was f ound that 0.2% flow stress increases with increasing Ir content within the single phase region of Nb solid solution, up to 6 mol%Tr and exhibits a dis tinct solid solution hardening. The 0.2% flow stress of the two-phase alloy s consisting of Nb solid solution and an intermetallic compound Nb3Ir, in t he alloys with 6 to 22 mol%Ir, also increases with increasing Ir content pr esumably by the precipitation hardening of the intermetallic phase. The str ength of the single phase compounds seemed to be very high and the measurem ent of 0.2% flow stress by compression tests was unsuccessful due to premat ure failure below 1473 K. The Vickers hardness of the compound was about 11 000 to 12000 MPa at room temperature.