Tensile behavior of a new single-crystal nickel-based superalloy with rhenium (CMSX-4) was studied at both room and elevated temperatures. The investigation also examined the influence of γ′ precipitates (size and distribution) on the tensile behavior of the material. Tensile specimens were prepared from single-crystal CMSX-4 in [001] orientation. The test specimens had the [001] growth direction parallel to the loading axis in tension. These specimens were given three different heat treatments to produce three different γ′ precipitate sizes and distributions. Tensile testing was carried out at both room and elevated temperatures. The results of the present investigation indicate that yield strength and ultimate tensile strength of this material initially increases with temperature, reaches a peak at around 800 °C, and then starts rapidly decreasing with rise in temperature. Both yield and tensile strength increased with increase in average γ′ precipitate size. Yield strength and temperature correlated very well by an Arrhenius type of relationship. Rate-controlling process for yielding at very high temperature (T ≥ 800 °C) was found to be the dislocation climb for all three differently heat-treated materials. Thermally activated hardening occurs below 800 °C whereas above 800 °C thermally activated softening occurs in this material.

Tensile behavior of a new single-crystal nickel-based superalloy (CMSX-4) at room and elevated temperatures

Origin of stray grain formation in single-crystal superalloy weld pools from heat transfer and fluid flow modeling

The kinetics, morphology and composition of the formation of TCP phases in an experimental alloy containing no tungsten is studied. At high temperature P phase forms after 20 h, whereas below 950°C the phases p and R occur. At lower temperatures a polycrystalline form of cr phase is observed which is meta-stable but acts as a nucleation site for the other phases. The phase occurrence and compositions are compared with a thermodynamic model using a rhenium-containing database, and reasonable agreement is found for the P, R and cs phases. However the model underestimates the stability of the p phase.

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Topologically close packed phases in an experimental rhenium-containing single crystal superalloy

A nickel-base superalloy, in particular for the production of large single-crystal components, consisting essentially of 6.0-6.8 % Cr, 8.0-10.0 % Co, 0.5-0.7 % Mo, 6.2-6.6 % W, 2.7-3.2 % Re, 5.4-5.8 % Al, 0.6-1.2 % Ti, 6.3-7.0 % Ta, 0.15-0.3 % Hf and 0.02-0.04 % C (all by weight), 40-100 ppm B and 15-50 ppm Mg, the remainder being made up of nickel and impurities.

Nickel-base superalloy

Selective electron beam melting (SEBM), which belongs to the additive manufacturing processes, is applied to produce samples from the single crystalline nickel-base superalloy CMSX-4. The influence of the high solidification rates on the microstructure and element distribution is investigated by OM, SEM, DSC, and EMPA. Solution heat treatments at different temperatures and holding times are applied to demonstrate the difference between conventionally cast and SEBM material. The results demonstrate that SEBM is able to produce superalloys with a degree of homogeneity which cannot be realized in conventional processes.

Solution Heat Treatment of the Single Crystal Nickel‐Base Superalloy CMSX‐4 Fabricated by Selective Electron Beam Melting

A team approach involving several turbine engine companies using the concepts of simultaneous engi-neering has been used to successfully develop CMSX-4 ® alloy for turbine blade applications. CMSX-4 al-loy is a second-generation, single-crystal cast nickel-base superalloy containing 3% Re and approximately 70% volume fraction of γ. The high level of balanced properties determined by labora-tory evaluation has been confirmed during field testing of the Solarγ Mars T-14000 industrial gas turbine with CMSX-4 single-crystal (SX) blades in both the coated and bare condition. A similar collaborative ap-proach has resulted in the successful development of CM 186 LCγ alloy for complex, directionally solidi-fied (DS) columnar grain vane segments. CM 186 LC alloy is a second-generation DS columnar grain cast nickel-base superalloy containing 3% Re and approximately 65% volume fraction of γ. Excellent com-ponent producibility and quality is demonstrated. Turbine engine testing is scheduled to commence by the end of 1993.

Development of two rhenium- containing superalloys for single- crystal blade and directionally solidified vane applications in advanced turbine engines

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Development of the Rhenium Containing Superalloys CMSX-4 & CM 186 LC for Single Crystal Blade and Directionally Solidified Vane Applications in Advanced Turbine Engines

A team approach utilizing simultaneous engineering has been used to develop CMSX-4 turbine airfoil components. CMSX-4 is a nickel-base single crystal superalloy containing 3% (wt) rhenium and a high 71% volume fraction of coherent {gamma}{prime} precipitate strengthening phase. The high level of balanced properties determined by extensive laboratory evaluation has been confirmed during engine testing the Allison AE 2100 and AE 301X engines, with the post-test condition of the components, including advanced Castcool{trademark} vane segments, being excellent. Also uncooled vane segments in CMSX-4 have exceeded engineering expectations.

G.L. Erickson

Papers

Development of two rhenium- containing superalloys for single- crystal blade and directionally solidified vane applications in advanced turbine engines

Development of the Rhenium Containing Superalloys CMSX-4 & CM 186 LC for Single Crystal Blade and Directionally Solidified Vane Applications in Advanced Turbine Engines

Allison engine testing CMSX-4{reg_sign} single crystal turbine blades and vanes