Compressive strength and creep properties of Ir-Nb-Zr alloys between 1473 and 2073 K

The microstructure and strength at 1473 and 2073 K and creep properties at 2073 K were investigated in three Ir-Nb-Zr alloys with the fee and L1(2) two-phase structure. The microstructure and lattice misfit were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffractometry (XRD). Compression and creep tests were performed, and their deformation structures were observed using SEM and TEM. At 1473 K, the strength of the Ir-Nb-Zr alloys was higher than that of the binary Ir-Nb and Ir-Zr alloys, but they were almost equivalent at 2073 K. However, the ternary alloys showed great improvement on creep at 2073 K. The time for the 2 pct creep strain of the Ir-Nb-Zr alloy was about 100 hours, while it was I hour for the binary alloys. The deformation mechanisms for compressive strength and creep resistance in these Ir-Nb-Zr alloys are discussed in terms of the deformation structure.