The effect of volume percent of fine γ’ on creep in Ds Mar-M200 + Hf

Effects of Cobalt in Nickel-Base Superalloys

“…In particular, cobalt was determined not to affect the strengthening y' fraction after the blade-type heat treatment, consistent with the observed insensitivity of creep rates to cobalt content, but after the disk-type heat treatment, the strengthening y' was determined to have decreased from about 36% to 29%, which was considered sufficient to lower the creep resistance (or increase the creep rate) by the observed one order of magnitude (2,27,28).…”

Retardation of σ-phase transformation in modified superalloy RR2072

“…It should be noticed that no fine ␥Ј particles were observed in the ␥ channels after exposure for 10 hours. They are very unstable so that they dissolved quickly, as reported by Jackson et al [8] With increasing exposure time, transformation occurred more extensively throughout the specimens, as illustrated in Figures 5(d) through (f). After exposure for 300 hours the number of plates slightly increased.…”

“…The Ta, Nb, and Ti elements are strong ␥Ј -phase formation ones. [8] Their 1. In the base RR2072 SX superalloy, -phase transformation starts in the dendrite cores.…”

Single Crystal Superalloys

“…A solution heat treatment is normally employed with single crystal superalloy castings to achieve the proper microstructure which consists of a fine γ' precipitate with little or no eutectic. Attainment of this microstructure is the key to achieving optimum mechanical properties in a single crystal [3,11]. This is in contrast to the practice with many high-strength, highvolume fraction conventionally cast polycrystalline alloys that are not given a solution heat treatment, because it lowers intermediate temperature creep ductility.…”