Nickel-Based Superalloy Composition for Low-Density High-Temperature Strength
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Solution Overview
Problem
Nickel-based superalloys used in turbomachines face challenges in achieving improved mechanical strength, creep resistance, corrosion resistance, oxidation resistance, and reduced density, particularly at high temperatures.
Innovation Solution
A nickel-based superalloy composition with specific mass percentages of elements such as aluminum, cobalt, chromium, hafnium, molybdenum, rhenium, tantalum, titanium, tungsten, and silicon, which enhances microstructural stability, creep resistance, and resistance to corrosion and oxidation, while reducing density and the risk of foundry defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional nickel-based superalloy compositions are used to ensure high temperature strength and creep resistance, then mechanical strength at high temperature is improved, but density increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ranges of multiple alloying elements (Al: 6-8%, Co: 12-15%, Cr: 4-8%, Mo: 0.5-4%, Re: 3.5-6%, Ta: 4-6%, Ti: 1-3%) to optimize the balance between mechanical strength and density. This compositional parameter optimization enables achieving high temperature strength while reducing density below 8.4 g/cm³
Solution Approach 2:
The patent creates a composite microstructure consisting of γ-Ni matrix with L1₂ ordered hardening precipitates (γ'-Ni3Al). This composite structure at the microstructural level provides both high temperature strength and improved density characteristics by combining different phases with complementary properties
2Strength
If alloy composition is optimized for mechanical strength, then creep resistance is improved, but resistance to corrosion and oxidation may deteriorate
Solution Approach 1:
The patent uses parameter changes by carefully balancing the content of elements affecting creep resistance (Re: 3.5-6%, Mo: 0.5-4%, Ta: 4-6%) with elements providing corrosion and oxidation resistance (Cr: 4-8%, Al: 6-8%). This simultaneous optimization of multiple compositional parameters achieves both creep resistance and environmental resistance
Solution Approach 2:
The patent creates a multi-functional composite microstructure where the γ-Ni matrix provides base stability, γ'-Ni3Al precipitates provide creep resistance through ordered hardening, and the specific alloying elements (Cr, Al) form protective surface layers. This composite structure delivers both mechanical strength and environmental resistance simultaneously
3Weight of moving object
If alloy composition is modified to reduce density, then weight is reduced, but mechanical strength and microstructural stability may worsen
Solution Approach 1:
The patent applies parameter changes by optimizing the specific ranges of alloying elements to achieve density reduction while maintaining strength. The controlled addition of lighter elements and precise balancing of alloy composition (with density < 8.4 g/cm³) ensures that weight reduction does not compromise mechanical properties
Solution Approach 2:
The patent maintains microstructural stability through its composite γ+γ' structure, where the ordered L1₂ precipitates provide thermal and microstructural stability even at reduced density. The specific composition ranges ensure phase stability and prevent unwanted precipitation during service
4Ease of manufacture
If conventional superalloy compositions are used, then manufacturing is simplified, but sensitivity to foundry defects and parasitic grain formation increases
Solution Approach 1:
The patent applies parameter changes by optimizing the compositional parameters to reduce sensitivity to foundry defects. The specific alloy composition ranges (particularly controlling elements like Mo, W, Re) improve fluidity and reduce hot tearing susceptibility during casting, while the controlled composition minimizes parasitic grain formation
Data Source
AI summary
The invention relates to a nickel-based superalloy comprising, in weight percentages, 6 to 8% of aluminum, 12 to 15% of cobalt, 4 to 8% of chromium, 0 to 0.2% of hafnium, 0.5 to 4% of molybdenum, 3.5 to 6% of rhenium, 4 to 6% of tantalum, 1 to 3% of titanium, 0 to 2% of tungsten, 0 to 0.1% of silicon, the remainder being nickel and inevitable impurities.