Very high temperature creep behavior of a single crystal Ni-based superalloy under complex thermal cycling conditions

Effect of the Prior Microstructure Degradation on the High Temperature/Low Stress Non-isothermal Creep Behavior of CMSX-4® Ni-based Single Crystal Superalloy

“…This is also true for MC2 alloy [16]. In fact, the observations of the ' microstructure at failure of the C-type structure clearly demonstrate that a N-type rafting occurred (Figures 10e and 10h).…”

“…Re is known, among other things, to slow down the diffusion processes [28,29] coarsening [30]. In fact, the rafting process ends after 24h at 1050°C/120 MPa for MC2 (Re-free) and after 100h for CMSX-4® under similar conditions [16,31]. Since a cuboidal /' microstructure is more resistant to non-isothermal creep than a Ntype rafted one (this point will be analyzed later in the discussion), it is believed that part of the CMSX-4® advantage over MC2 is due to this slower N-type ' directional coarsening.…”

“…The typical creep behaviors of the first generation MC2 alloy [16] and CMSX-4®are compared in Figure 11, under type I thermal cycling. A C-type structure at the beginning of thermal cycling is investigated here.…”

“…In particular, the new certification procedures of helicopter gas turbines now include complex temperature/angular velocity histories, and sometimes thermal cycling, as for, e.g., endurance or accelerated mission (ASMET) engine tests. However, the literature analyzing the effect a such complex very high temperature creep loadings on the durability of Ni-based single crystal superalloys is scarce and mainly limited to two research teams [9][10][11][12][13][14][15][16], the pioneering works being performed on polycrystalline alloys by Rowe and Freeman [17][18]. In this context, two specific test benches were developed at the Pprime Institute (THALIE and MAATRE burners) as well as specific procedures using radiative furnaces in order to mimic realistic conditions in a controlled laboratory environment [8,16]).…”

Creep properties and deformation mechanism of the containing 4.5Re/3.0Ru single crystal nickel-based superalloy at high temperatures

“…5, which is attributed to the super-saturation precipitation of the  former elements during cooling, and had been verified by the non-isothermal creep tests of the single crystal nickel-based superalloys in the ranges of 1050-1200 o C [40][41][42]. But it is understood from the amplification morphology in Fig.…”