The evolution of wrought age-hardenable superalloys

Abstract

The discovery of γ′ hardening early in the 20th century seeded a continuous evolution of a remarkable family of alloys, known as the superalloys. The sequence of their development will be traced in this article. The theories of alloying and hardening mechanisms will be discussed as each played an essential role in the progressive development of the superalloys, as did a number of processing discoveries that are reviewed here.

In situ strained Inconel 718 superalloy studied by thermoelectric power technique

“…The group of high temperatures treatments A-D, presents a clear opposed behaviour (σ Y < 350 MPa) and they will be identified as states with non-desirable phases (SNDP). It is well known, ␥ and ␥ phases have crystal ordered cells (L12 and BCT) [3,20] and this order gives to superalloys an increase in mechanical properties which is in agreement with these results. Another feature can be observed in Fig.…”

“…Inconel 718 belongs to the Ni-Fe base superalloys principally strengthened by the precipitation of the ordered body-centered tetragonal (BCT) ␥ phase, a DO 22 type. Aerospace service conditions during important exposure times can get closer to conditions that can promote non-desirable phases (∼700 • C), for example ␥ → Ni 3 Nb (␦) [3]. But another important point for researches of the Inconel 718 system is the plastic strain and the internal stress developed during the conception of aerospace pieces.…”

Changes in the thermoelectric power of a Ni base superalloy induced by elastic and plastic strain

“…For HT C, D and E an increase of the strength ( Y > 600 MPa) is clearly observed due to the ␥ phase. It is well known that the ␥ phase has a crystal ordered cell L12 [16,17] and this order gives to the superalloys, an increase in their mechanical properties, which is in agreement with these results. Another feature can be observed in Fig.…”

Reaction Scheme and Liquidus Surface in the Al-Rich Section of the Al-Cr-Ni System

“…BECAUSE of the well-known technological importance (for example, the reviews by Stickler, [1] Anton, [2] Decker, [3] and the references quoted therein), the Ni-rich part of the Al-Cr-Ni system early on was subject to experimental investigations [4][5][6] resulting in quite complete knowledge of the Al-Cr-Ni constitution within the composition range Ni-NiAl-Cr (e.g., Velikanova et al [7] and Raghavan [8] ). For the remaining, more Al-rich part of the system, however, only the exploratory work of Rosell-Laclau et al [9,10] and the crystal structure determination of the ternary phase j-Al 76.2 Cr 18.0 Ni 5.8 (space group P6 3 , a = 1.7674 nm, and c = 1.2516 nm by Sato et al [11] ; in the following labeled s 1 ) existed until Grushko et al [12] reported isothermal sections for 1000°C and 900°C.…”