TY - JOUR
T1 - High temperature strength of Ir-based refractory superalloys
AU - Yamabe-Mitarai, Yoko
AU - Ro, Yoshikazu
AU - Nakazawa, Shizuo
AU - Harada, Hiroshi
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2000
Y1 - 2000
N2 - The purpose of this paper is to understand the high-strength and deformation mechanism of new-generation 'refractory superalloys'. Refractory superalloys are defined as alloys that have an fcc and L12 two-phase coherent structure and yet considerably high melting points. This paper examines compressive strength up to 1800°C and creep behavior at 1500°C of Ir-V, -Ti, -Nb, -Ta, -Hf, and -Zr binary refractory superalloys. It is indicated that the precipitation-hardening effect depends on L12 precipitate morphology. Plate-like precipitates are more effective for precipitation hardening than cuboidal precipitates. Shearing of precipitates was observed in the alloy with plate-like precipitates using TEM. When plate-like precipitates form, a dislocation cannot bypass around a plate, thus being forced to shear a precipitate. However, high-coherency strain energy at the interface prevents the dislocation motion. Therefore, large precipitation hardening appeared in the alloy with plate-like precipitates. On the other hand, the creep resistance of the alloy with plate-like precipitates was smaller than that of the alloy with cuboidal precipitates because discontinuous coarsening occurs and the microstructure becomes coarse in the alloy with plate-like precipitates.
AB - The purpose of this paper is to understand the high-strength and deformation mechanism of new-generation 'refractory superalloys'. Refractory superalloys are defined as alloys that have an fcc and L12 two-phase coherent structure and yet considerably high melting points. This paper examines compressive strength up to 1800°C and creep behavior at 1500°C of Ir-V, -Ti, -Nb, -Ta, -Hf, and -Zr binary refractory superalloys. It is indicated that the precipitation-hardening effect depends on L12 precipitate morphology. Plate-like precipitates are more effective for precipitation hardening than cuboidal precipitates. Shearing of precipitates was observed in the alloy with plate-like precipitates using TEM. When plate-like precipitates form, a dislocation cannot bypass around a plate, thus being forced to shear a precipitate. However, high-coherency strain energy at the interface prevents the dislocation motion. Therefore, large precipitation hardening appeared in the alloy with plate-like precipitates. On the other hand, the creep resistance of the alloy with plate-like precipitates was smaller than that of the alloy with cuboidal precipitates because discontinuous coarsening occurs and the microstructure becomes coarse in the alloy with plate-like precipitates.
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U2 - 10.2320/jinstmet1952.64.11_1068
DO - 10.2320/jinstmet1952.64.11_1068
M3 - Article
AN - SCOPUS:0034475961
VL - 64
SP - 1068
EP - 1075
JO - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
JF - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
SN - 0021-4876
IS - 11
ER -