Low Rhenium Nickel Superalloy Composition for Turbine Blades
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Solution Overview
Problem
Current nickel-base superalloys with low rhenium (Re) content fail to provide the necessary high temperature characteristics, thermal mechanical properties, and oxidation resistance required for aerospace applications, particularly in turbine nozzles and shrouds, due to the cost and global shortage of Re.
Innovation Solution
Development of nickel-base superalloy compositions with reduced Re content, balancing alloying elements such as chromium, cobalt, molybdenum, tungsten, tantalum, aluminum, and hafnium to achieve thermal mechanical properties and oxidation resistance comparable to second-generation superalloys, while maintaining a Re ratio less than 0.3 and P-values below 3360.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If rhenium content is reduced to lower cost and address global shortage, then material cost decreases, but high temperature creep resistance and thermal mechanical properties deteriorate
Solution Approach 1:
The patent changes the compositional parameters by reducing rhenium content from typical levels (3-6 wt%) to below 3 wt%, and simultaneously adjusts other alloying element parameters (increasing cobalt to 7-9 wt%, tungsten to 5-7 wt%, molybdenum to 1.5-2.5 wt%) to maintain the desired mechanical properties and creep resistance at high temperatures
Solution Approach 2:
The patent creates a composite alloy composition by combining multiple strengthening elements (cobalt, tungsten, molybdenum, tantalum, aluminum) in specific proportions to achieve the desired high temperature performance without relying heavily on rhenium, effectively creating a multi-element strengthened nickel base superalloy system
2Use of energy by moving object
If operating temperature is increased to improve engine efficiency, then engine efficiency increases, but material strength and structural integrity deteriorate
Solution Approach 1:
The patent modifies the alloy composition parameters to enable operation at higher temperatures by increasing the content of high-temperature strengthening elements (cobalt 7-9 wt%, tungsten 5-7 wt%, tantalum 6-8 wt%) and optimizing precipitate-forming elements (aluminum 5-7 wt%) to maintain material strength at elevated operating temperatures up to 90% of melting point
3Reliability
If oxidation resistance is improved for environmental degradation protection, then environmental resistance increases, but alloy composition complexity increases
Solution Approach 1:
The patent optimizes the composition parameters for oxidation resistance by maintaining chromium content at 6-8 wt% for protective oxide scale formation, adding hafnium at 0.1-0.5 wt% to enhance hot corrosion resistance, and controlling aluminum content at 5-7 wt% to ensure stable alumina scale formation, thereby achieving improved environmental resistance through controlled compositional parameters
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compositions exhibit improved creep rupture, high temperature oxidation resistance, and sustained peak low cycle fatigue properties comparable to second-generation superalloys, even with reduced Re content, making them suitable for high-temperature components like turbine blades and nozzles.
Implementation Method 1
The addition of about 3 wt% Re to superalloy compositions provides about a 50°F (28 °C) improvement in rupture creep capability
Implementation Method 2
Nickel-base superalloys are used extensively throughout the aeroengine in turbine blade, nozzle, and shroud applications because they maintain their strength at up to 90% of their melting temperature
Implementation Method 3
Superalloys are used for these demanding applications because they maintain their strength at up to 90% of their melting temperature and have excellent environmental resistance
Implementation Method 4
U.S. Patent 6,074,602 is directed to nickel-base superalloys suitable for making single-crystal castings
Data Source
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AI summary
Low rhenium nickel base superalloy compositions and articles formed from the superalloy composition are provided. The nickel base superalloy composition includes in percentages by weight: about 5-8 Cr; about 6.5-9 Co; about 1.3-2.5 Mo; about 4.8-6.8 W; about 6.0-7.0 Ta; if present, up to about 0.5 Ti; about 6.0-6.4 Al; about 1-2.3 Re; if present, up to about 0.6 Hf; if present, up to about 0-1.5 C; if present, up to about 0.015 B; the balance being nickel and incidental impurities. Exemplary compositions are characterized by an Re ratio defined as the weight % of Re relative to the total of the weight % of W and the wt % of Mo, of less than about 0.3. Exemplary articles include airfoils for gas turbine engine blades or vanes, nozzles, shrouds, and splash plates.