High Temperature Mechanical Properties of CMSX4+Yttrium Single-Crystal Nickel-Base Superalloys SRR 99 and CMX-4

Abstract

CMSX4+Y, a highly strengthened rhenium-containing second generation single-crystal nickel-base superalloy, has been studied by creep as well as low cycle and thermomechanical fatigue in the temperature range of 500°C to 1100°C. The alloy exhibits very good high temperature mechanical properties better or comparable with other single crystal superalloys. The thermomechanical fatigue resistance is comparable with low cycle fatigue one and is cycle-shape dependent.The observation of fracture surfaces shows that fracture induced by creep damage is internal and starts from pore-initiated cracks, while fatigue damage starts on the external surface and propagates inward in stage II mode.

Effects of Y and La Additions on the Processing and Properties of a Second Generation Single Crystal Nickel‐Base Superalloy CMSX‐4®

“…These Y and La-rich phases were mostly observed in the interdendritic regions, adjacent to the coarse cellular ' areas formed during the terminal stages of the directional solidification casting process [7]. These Y and La-rich phases are expected to be combinations of oxides, sulphides and/or oxysulphides of Y and La; in addition, in the materials with high Y+La contents, Ni-Y and Ni-La eutectics are also expected to be present [2,4,5,6,8,9]. Examination of the Ni-Y and Ni-La phase diagrams indicates that Y and La have no major solubility in Ni, and in addition most of the Ni-Y and Ni-La eutectics have relatively low melting points [2].…”

“…casting and solution heat treatment, as well as during service e.g. decline in mechanical performance and alloy stability [1,3,4,5]. These issues, although known, have not been sufficiently quantified or understood.…”

Study on creep behaviors of nickel-based single-crystal alloys considering microstructure evolution

“…Nickel-based single-crystal superalloys are widely used in the turbine blades of aeroengines due to its good high temperature resistance (Marchionni et al, 1992). The high temperature mechanical properties of nickel-based single-crystal superalloys are closely related to the γ 0 reinforced phase.…”