Yi Tan*, Hisao Tanaka*, Chaoli Ma*, Akio Kasama*, Ryohei Tanaka*, Yoshinao Mishima** and Shuji Hanada***
* Japan Ultra-high Temperature Materials Research Institute (JUTEMI), Ube 755-0001 ** Department of Materials Science and Engineering, Tokyo Institute of Technology, Yokohama 226-8502 *** Institute for Materials Research, Tohoku University, Sendai 980-8577Mechanical behavior of binary Nb-Ir alloys was investigated by compression tests at the temperatures ranging from room temperature to 1773 K. It was found that 0.2% flow stress increases with increasing Ir content within the single phase region of Nb solid solution, up to 6 mol%Ir and exhibits a distinct solid solution hardening. The 0.2% flow stress of the two-phase alloys consisting of Nb solid solution and an intermetallic compound Nb3Ir, in the alloys with 6 to 22 mol%Ir, also increases with increasing Ir content presumably by the precipitation hardening of the intermetallic phase. The strength of the single phase compounds seemed to be very high and the measurement of 0.2% flow stress by compression tests was unsuccessful due to premature failure below 1473 K. The Vickers hardness of the compound was about 11000 to 12000 MPa at room temperature.
niobium-iridium alloy, intermetallic compound, compressive strength, niobium base alloy, solid solution hardening