TiAl Alloy Microstructure for Strength-Ductility-Creep Balance
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Solution Overview
Problem
Existing TiAl-based alloys face challenges in simultaneously achieving high strength, ductility, and creep properties, with current solutions often requiring the sacrifice of one or more of these properties.
Innovation Solution
A TiAl-based alloy composition with specific atomic percentages of Al, β-stabilizing elements, and controlled heat treatment processes to form (α2/γ) lamellar grains and cellular or secondary lamellar structures, with controlled volume fractions of these structures to enhance strength, ductility, and creep properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a grain boundary γ phase is precipitated to improve strength and ductility, then strength and ductility are improved, but creep properties deteriorate significantly
Solution Approach 1:
The patent applies local quality by creating different microstructural zones within the alloy. The γ phase is selectively precipitated at grain boundaries to improve strength and ductility, while the interior regions maintain structures that preserve creep resistance. This spatial differentiation of phases allows simultaneous optimization of competing properties in different locations of the material.
Solution Approach 2:
The patent creates a composite microstructure consisting of multiple phases (γ phase at grain boundaries, α2 and other phases in interior regions) with distinct functions. The γ phase provides strength and ductility enhancement, while other phases maintain creep resistance, achieving a composite material system where different components address different performance requirements.
2Strength
If γ phase precipitation is used to achieve high strength, then strength is improved, but it becomes difficult to maintain desirable creep properties
Solution Approach 1:
The patent applies local quality by creating different microstructural zones within the alloy. The γ phase is selectively precipitated at grain boundaries to improve strength and ductility, while the interior regions maintain structures that preserve creep resistance. This spatial differentiation of phases allows simultaneous optimization of competing properties in different locations of the material.
Solution Approach 2:
The patent creates a composite microstructure consisting of multiple phases (γ phase at grain boundaries, α2 and other phases in interior regions) with distinct functions. The γ phase provides strength and ductility enhancement, while other phases maintain creep resistance, achieving a composite material system where different components address different performance requirements.
3Strength
If conventional TiAl-based alloys are used to achieve one property (strength, ductility, or creep), then that property is improved, but other properties must be sacrificed
Solution Approach 1:
The patent creates a composite microstructure consisting of multiple phases (γ phase at grain boundaries, α2 and other phases in interior regions) with distinct functions. The γ phase provides strength and ductility enhancement, while other phases maintain creep resistance, achieving a composite material system where different components address different performance requirements.
Solution Approach 2:
The patent applies local quality by creating different microstructural zones within the alloy. The γ phase is selectively precipitated at grain boundaries to improve strength and ductility, while the interior regions maintain structures that preserve creep resistance. This spatial differentiation of phases allows simultaneous optimization of competing properties in different locations of the material.
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 achieves a balance of desired strength, ductility, and creep properties through controlled microstructural refinement, improving high-temperature performance and manufacturability.
Implementation Method 1
the TiAl-based alloy is held at a first temperature for a predetermined period of time in an (α + γ) two-phase region, an α single-phase region, a (β + α) two-phase region, or a (β + α + γ) three-phase region
Implementation Method 2
a cellular structure or a secondary lamellar structure precipitated at (α 2 /γ) lamellar grain boundaries
Data Source
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AI summary
The present disclosure provides a TiAl-based alloy combining the desired strength, ductility, and creep properties, and a method for producing the same. A TiAl-based alloy according to the present disclosure comprising, in atomic percent, Al: 45% to 49 %, β-stabilizing elements: 3% to 11%, Ni: ≤ 1.0%, C: ≤ 0.6%, Si: ≤ 0.5%, O: ≤ 1.5%, the balance being Ti and inevitable impurities, in which the β-stabilizing elements are any of Cr, Nb, V, Mn and Mo or a combination thereof, the metal structure comprises (α2/γ) lamellar grains and a cellular structure or a secondary lamellar structure precipitated at (α2/γ) lamellar grain boundaries, the cellular structure is a (β/γ) cellular structure or an (α2/γ/β) cellular structure, the secondary lamellar structure has (α2/γ) lamellar grains having a grain diameter smaller than that of the (α2/γ) lamellar grains, and a volume fraction of the cellular structure or the secondary lamellar structure is 1 vol% or more and 50 vol% or less.