Compressive creep properties of Ir-base refractory superalloys

Abstract

Ir-base alloys with the fcc and L1 2 -Ir 3 X (X ϭ Nb, Zr) two-phase structure have been developed as next-generation high-temperature materials. The compressive creep behavior of Ir-Nb and Ir-Zr alloys was investigated at 2073 K under 137 MPa. The effect of addition of the third element, Zr, on the creep behavior of an Ir-Nb alloy was also investigated at 2073 K for 137 MPa. The creep rate became two orders lower by addition of a small amount of Zr. The lattice misfit change between the fcc and L1 2 two phase by addition of Zr and the deformation structure in binary and ternary alloys after a creep test were also investigated. The creep behavior is discussed in terms of the lattice misfit, precipitate shape, and their distribution.

Ir–Nb–Si ternary refractory superalloys with a three-phase fcc/L12/silicide structure for high-temperature applications

“…12(d)). This intergranular mode has been found in IreNbeZr [30] and IreNbeNi [4] ternary alloys. All this evidence strongly supports the ideas that the failure mode of Ire Nb-based alloys at room and high temperatures is independent of third-element additions and that the coherence of the precipitateematrix interface and grain boundary does not play an important role.…”

“…These interfaces and boundaries are the promising sites for crack initiation and propagation under compressive loading at high temperature. However, among the six boundaries, the F/S and L/S interfaces are the most critical ones because there are the largest property mismatch and obviously structural difference between the fcc and the silicides (D0 c (Ir 3 Si), C23 (Ir 2 Si), and B31 (IrSi) [30] to fcc). The above property mismatch causes interface or grain boundary debonding.…”

“…IreNbeNi, IreNbeZr, and IrePteAl ternary [3,4,12,14,30] and IreNbeNieAl quaternary alloys [8,9] have also been developed to investigate the effect of multi-alloying on the hardening of the Ir-based alloys. The addition of the third or fourth element into the Ir-based alloys benefits both the strength and the creep resistance at elevated temperatures.…”

“…For example, the strength of Ire15NbexNi increases with Ni at a content of Ni of less than 10 mol% [4], and, at 1650 C and 137 MPa, the steady-state creep rate of Ire 15Nbe1Ni is 1.2 Â 10 À8 s À1 [12]. In the cases of IreNbeZr ternary alloys, the significant creep resistance is achieved if the alloys have a single L1 2 phase [30]. With a single L1 2 phase, IreNbeZr ternary alloys have a creep lifetime of more than 150 h at a temperature of 1800 C and a stress of 137 MPa.…”

A Novel Amperometric Transducer Electrode with Iridium‐Niobium Binary Alloys

“…Accordingly, Platinum has almost always been used in the materials of amperometric biosensor electrodes; carbon is an exception [8 -12]. Certain binary Ir alloys, i.e., Ir-Nb, IrZr, and Ir-Nb-Zr, have been noted as having high temperature materials [13,14]. However, the prices of rare metals including Ir have been fluctuating widely because of the global economic crisis and/or because they are mined in limited quantities.…”