Nickel-Base Alloy Phase Stability Above 900°C
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Solution Overview
Problem
High-temperature nickel-base alloys like C263 lose creep resistance at exhaust-gas temperatures above 900°C, leading to structural failures and power loss in turbochargers and engines due to inadequate stability of strength-increasing phases.
Innovation Solution
A high-temperature nickel-base alloy with a modified composition, including 0.04-0.1% C, 24-28% Cr, 0.5-3% Ti, and 17-21% Co, which shifts the stability of the gamma prime phase to higher temperatures while stabilizing other phases at lower temperatures, enhancing high-temperature strength, creep resistance, and thermal corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the material composition is based on C263 (Nicrofer 5120 CoTi), then the material can be produced and used for heat shields, but it loses creep resistance at temperatures above 900°C due to instability of the gamma prime phase
Solution Approach 1:
The patent applies parameter changes by modifying the alloy composition parameters: increasing Cr content to 24-28% (from 19-21%), adjusting Ti to 0.5-3% (from 1.9-2.4%), adding Nb (0.001-0.1%), and optimizing C (0.04-0.1%). These compositional parameter changes shift the gamma prime phase stability to higher temperatures, enabling creep resistance above 900°C while maintaining other beneficial properties.
2Strength
If the Cr content is increased to 24-28% and Ti to 0.5-3%, then the gamma prime phase stability is shifted to higher temperatures, but the composition range becomes more restricted compared to conventional alloys
Solution Approach 1:
The patent defines specific parameter ranges for each alloying element to achieve the desired gamma prime phase stability. By setting Cr at 24-28%, Ti at 0.5-3%, Co at 17-21%, and adding controlled amounts of Nb and C, the patent creates an optimized compositional parameter space that balances high-temperature strength with manufacturability.
Solution Approach 2:
The patent creates a composite alloy system combining multiple elements (Ni-Cr-Co-Ti-Mo-Al-Ti-Nb) that work synergistically. The gamma prime phase (Ni3(Al,Ti)) is enhanced through the combined effect of Al and Ti, while Cr provides oxidation resistance and Co stabilizes the austenitic matrix, creating a multi-functional composite material system.
3Strength
If the alloy composition is modified to enhance gamma prime phase stability, then creep resistance improves, but other phases (e.g., eta phase) may form at lower temperatures
Solution Approach 1:
The patent carefully balances compositional parameters to control phase stability. By optimizing the Ti/Al ratio and controlling Nb content, the patent shifts the eta phase (Ni3Ti) formation temperature to lower ranges while maintaining gamma prime stability at high temperatures. The controlled C content (0.04-0.1%) also helps prevent unwanted carbide precipitation.
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 alloy exhibits improved high-temperature strength, creep resistance, and fatigue resistance, maintaining structural integrity and reducing deformation in applications above 900°C, with enhanced thermal corrosion resistance and industrial-scale production feasibility.
Implementation Method 1
The invention relates to a high-temperature nickel-base alloy... which shifts the stability of the gamma prime phase to higher temperatures... activating additional hardening mechanisms
Data Source
AI summary
A high-temperature nickel-base alloy consists of (in wt. %): C: 0.04-0.1%, S: max. 0.01%, N: max. 0.05%, Cr: 24-28%, Mn: max. 0.3%, Si: max. 0.3%, Mo: 1-6%, Ti: 0.5-3%, Nb: 0.001-0.1%, Cu: max. 0.2%, Fe: 0.1-0.7%, P: max. 0.015%, Al: 0.5-2%, Mg: max. 0.01%, Ca: max. 0.01%, V: 0.01-0.5%, Zr: max. 0.1%, W: 0.2-2%, Co: 17-21%, B: max. 0.01%, O: max. 0.01%, with the rest being Ni, as well as melting-related impurities.