Ni-Based Single Crystal Superalloy TCP Phase Control
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Solution Overview
Problem
Ni-based single crystal superalloys face challenges in achieving balanced high-temperature strength and oxidation resistance, with existing alloys either compromising on creep strength or oxidation resistance, and the compositional ratios of alloying elements are difficult to control to prevent TCP phase precipitation and optimize lattice constants.
Innovation Solution
A Ni-based single crystal superalloy composition with specific ranges of Al, Ta, W, Re, Cr, Ru, and Nb is optimized to control lattice constants and prevent TCP phase precipitation, while incorporating additional elements like Mo, Hf, and Co to enhance high-temperature strength and oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the compositional ratio of Re is increased to improve high-temperature creep strength, then the creep strength increases, but excessive Re forms TCP phase which lowers the creep strength
Solution Approach 1:
The invention changes the compositional parameters by limiting Re content to 3.0-8.0 wt% and adding Ru (1.0-14.0 wt%) and Nb (1.0-4.0 wt%) to modify the phase formation behavior. This parameter optimization prevents TCP phase precipitation while maintaining high creep strength through controlled solid solution strengthening.
2Object-affected harmful factors
If Cr content is increased to improve oxidation resistance, then oxidation resistance improves, but the lattice constant control becomes more difficult affecting creep strength
Solution Approach 1:
The invention creates a composite alloy system combining Cr (3.0-7.0 wt%) for oxidation resistance with Ru (1.0-14.0 wt%) and Nb (1.0-4.0 wt%) for lattice constant control. This multi-element composite approach allows simultaneous optimization of both oxidation resistance and creep strength by balancing the effects of different alloying elements on the γ and γ' phase lattice constants.
3Strength
If Ru is added to improve high-temperature strength, then strength increases, but oxidation resistance and corrosion resistance are lowered
Solution Approach 1:
The invention applies local quality by distributing Ru (1.0-14.0 wt%) and Cr (3.0-7.0 wt%) to different functional roles within the alloy system. Ru provides solid solution strengthening and TCP phase suppression in the matrix, while Cr forms protective oxidation-resistant layers on the surface. This spatial-functional differentiation allows both elements to contribute their beneficial effects while minimizing their adverse impacts.
4Strength
If the lattice constant of γ' phase is made lower than γ phase to improve creep strength, then creep strength improves, but precise control of lattice constant becomes difficult
Solution Approach 1:
The invention uses multiple alloying elements (Ru, Nb, Cr, Ta, W) whose concentrations can be independently adjusted to control the lattice constants of both γ and γ' phases. By changing the compositional parameters of these elements, the lattice misfit can be precisely controlled to achieve the desired lattice constant relationship (aγ' < aγ) for optimal creep strength while maintaining manufacturing feasibility.
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 optimized alloy achieves improved high-temperature strength and oxidation resistance, with a creep rupture lifetime of 1400 hours at 1100°C and 137 MPa and minimal mass change in high-temperature oxidation tests, demonstrating excellent balance in both mechanical and environmental performance.
Implementation Method 1
The alloy is a so-called precipitation-hardened alloy, and has a morphology where a precipitation phase, γ'-phase is precipitated in the matrix phase, γ-phase.
Implementation Method 2
The above-mentioned Ni-based single crystal superalloy is obtained through solution treatment at a predetermined temperature followed by aging treatment.
Implementation Method 3
The above-mentioned Ni-based single crystal superalloy is obtained through solution treatment at a predetermined temperature followed by aging treatment.
Data Source
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AI summary
Provided is an Ni-based single crystal superalloy wherein the ingredients have a composition containing, as ratio by mass, from 5.0% by mass to 7.0% by mass of Al, from 4.0% by mass to 8.0% by mass of Ta, from 0% by mass to 2.0% by mass of Mo, from 3.0% by mass to 8.0% by mass of W, from 3.0% by mass to 8.0% by mass of Re, from 0% by mass to 0.50% by mass of Hf, from 3.0% by mass to 6.0% by mass of Cr, from 0% by mass to 9.9% by mass of Co, from 1.0% by mass to 14.0% by mass of Ru, and from 0.1 % by mass to 4.0% by mass of Nb, with the balance of Ni and inevitable impurities. The alloy prevents TCP phase precipitation at high temperatures, therefore having improved strength at high temperatures and having oxidation resistance at high temperatures. Specifically, the invention is to provide a high-performance Ni-based single crystal superalloy having well balanced high-temperature strength and high-temperature oxidation resistance in practical use. The invention is also to provide the Ni-based single crystal superalloy having sufficient characteristics in point of "heat treatment window" that should not be overlooked in practical use.