Critical Hafnium Content for Extended Lifetime of AM1 Single Crystal Superalloy

Very high cycle fatigue durability of an additively manufactured single-crystal Ni-based superalloy

“…Regarding oxidation, Juillet et al demonstrated that the instantaneous parabolic rate (kp) constants could not be calculated in an AM IN-718 superalloy due to enhanced growth of the oxides in comparison with the forged counterparts and related this to the significantly higher density of internal defects assessed by transmission electron microscopy (TEM) [60]. As a result, the selective outward diffusion of the most oxidizable elements to form the oxide scale brings about the precipitation of the strong carbide and nitride formers underneath [61]. initiation and no evidence of recrystallization close to secondary cracks in PBF-E processed specimens has been observed (see, e.g., Fig.…”

Kinetic oxidation model including the transient regime for a single crystal nickel-based superalloy over the temperature range 750–1300 °C

“…This slightly lower k p obtained for the AM1 could be attributed to the presence of hafnium in the AM1 alloy. Indeed, Hf can be found in grain boundaries of α-Al 2 O 3 [6] and is known to have a beneficial effect on the oxidation kinetics of Ni-Al [31,32].…”

“…Isothermal oxidations are reported only at 1100°C [5]. Cyclic oxidation data for this alloy are reported only at 1100°C [4] and 1150°C [6]. Over these temperatures, gamma prime precipitates volume fraction is too low to ensure good creep The quantification of the oxidation kinetics is important since it allows to predict the depletion of the γ' precipitates and thus the influence of oxidation on the mechanical properties of the part [11][12][13].…”

“…In the literature, few studies report the oxidation behavior of uncoated AM1 [4][5][6] and only at the highest temperatures of use. Isothermal oxidations are reported only at 1100°C [5].…”

Oxidation behavior and outward diffusion of Al along oxide grain boundaries of FeCrAl alloys overdoped with Zr and Hf by means of Atom Probe Tomography (APT)

“…The effect of the RE depends on their distribution and concentration [6]. Most of the recent works suggest that the RE concentration has to be around a few hundred parts per million [14][15][16]. Overdoping, however, can generate disadvantageous effects, for instance, formation of a second phase such as yttrium aluminum oxide (Y 3 Al 5 O 12 -YAG) [17,18].…”