A 5th Generation SC Superalloy with Balanced High Temperature Properties and Processability

Abstract

A 5th generation single crystal (SC) superalloy TMS-196 with improved microstructural stability and environmental properties was designed with using NIMS Alloy Design Program and evaluated experimentally. It was found that TMS-196 has a very stable microstructure even after 1000h creep at 1100 C and also very well balanced creep, TMF and environmental properties. TMS-196 also had excellent SC castability; sound cooling blades of up to 300mm long were successfully cast.

A New Oxide Morphology Map: Initial Oxidation Behavior of Ni-Base Single-Crystal Superalloys

“…Alloys in group A in Figures 3(a) and (b) developed a thin Al 2 O 3 layer and/or spinel or complex oxides on the specimen surface. Similar oxide morphologies are observed in TMS-196 [20] and TMS-198, [2] and for TMS-196, Ni(Al,Cr) 2 O 4 as spinel oxides was observed with continuous Al 2 O 3 formation. On the contrary, the alloys in group B in Figures 3(c) through (e) formed thick NiO oxide layers at the top of the oxide scale with approximately 10 lm thickness, followed by either Al 2 O 3 or a complex oxide internal subscale.…”

“…The alloys were designed and developed via an alloy design program [16] at the National Institute for Materials Science (Ibaraki, NIMS) in Japan and have the following composition ranges: 0 to 15.4 Co, 0 to 30.5 Cr, 0 to 1.9 Mo, 0 to 4.4 W, 11.5 to 18.9 Al, 0 to 2.5 Ti, 0 to 1.3 Nb, 0 to 3.6 Ta, 0 to 0.7 Hf, 0 to 2.6 Re, 0 to 5.1 Ru, 0 to 4.1 Si, 0 to 0.3 C in at pct, and the balance Ni. Compositions of selected example alloys [2,[17][18][19][20] were given in Table I. The alloys were cast into single-crystal rods by means of a directional solidification casting furnace, and heat treated with standard two-step treatments.…”

Thermal–mechanical fatigue behaviour of a new single crystal superalloy: Effects of Si and Re alloying

“…The results indicate that the TMF performance of STAL-15 -which is not far from highly alloyed materials such as CMSX-4 -may be due to the absence of any such instability; none of the STAL-15 variants considered here show any precipitation of TCP phases during TMF testing up to 950°C. Where TCP phases -which are often rich in Cr, Re, W and Mo -arise, they are often considered to be detrimental to alloys aiming for high temperature applications, see for example [15,17,40]. These elements strengthen the c-phase and if the elements instead form TCP phases, creep resistance is impaired.…”

Classification and microstructural stability of high generation single crystal Nickel-based superalloys

“…th generation were mainly developed by the National Institute of Material Science (NIMS) in Japan. According to the NIMS Alloy Design software (NIMS-ADP) [36] material parameters including phase composition and volume fractions, alloy density, phase stability, lattice misfit, creep strengths were taken into account [22,35]. To improve the oxidation resistance, Cr content was increased in the highest generation alloys to 4,6 wt.…”