High-Entropy Alloy Composition for Suppressing Coarse Intermetallic Phases
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Solution Overview
Problem
Existing high-entropy alloy materials face challenges in controlling the coarse growth or aggregation of undesired intermetallic compound phases, such as η phase and Laves phase, which deteriorate mechanical characteristics and corrosion resistance as the volume of the alloy product increases, particularly due to difficulties in managing the cooling rate during pseudo-solution heat treatment.
Innovation Solution
The alloy composition is optimized with specific ranges for Co, Cr, Fe, Ni, Mo, Ti, and optionally Ta or Nb, with controlled total content of Ti and Ta/Nb, ensuring ultrafine particles are dispersed and precipitated, suppressing the formation of η phase and Laves phase to 5 area% or less, and maintaining a face-centered cubic structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the volume of alloy product is increased, then productivity is improved, but manufacturing precision deteriorates due to difficult control of cooling rate in pseudo-solution heat treatment
Solution Approach 1:
The patent modifies the chemical composition parameters of the alloy by adding specific elements (Ta, Nb, Hf, Zr, or Y) within defined concentration ranges (0.01-5 at% each). This composition adjustment changes the physical properties of the alloy, specifically improving its thermal conductivity and heat capacity characteristics, which enables better cooling rate control during heat treatment of large-volume products.
Solution Approach 2:
The patent performs preliminary alloy composition design and preparation before the actual product manufacturing. By pre-adjusting the elemental composition to include specific amounts of Ta/Nb/Hf/Zr/Y elements, the alloy is prepared in advance to have optimized thermal properties that will facilitate proper cooling rate control during subsequent pseudo-solution heat treatment of large-volume products.
2Strength
If ultrafine particles are dispersed and precipitated in matrix crystal, then mechanical characteristics are improved, but reliability deteriorates when undesired intermetallic compound phase grows coarsely or aggregates
Solution Approach 1:
The patent introduces Ta, Nb, Hf, Zr, or Y elements as intermediary elements that mediate between the matrix crystal and the Ti-containing phases. These intermediary elements have atomic radii larger than Co, Cr, Fe, and Ni, and they interact with Ti to form stable compounds or modify the interface energy, thereby preventing the coarse growth and aggregation of undesired intermetallic compound phases while maintaining ultrafine particle dispersion.
Solution Approach 2:
The patent changes the chemical composition parameters by adding specific elements (Ta, Nb, Hf, Zr, or Y) in controlled amounts (0.01-5 at% each). This composition modification alters the thermodynamic and kinetic parameters of phase formation, suppressing the coarsening and aggregation of intermetallic compounds while preserving the beneficial ultrafine particle dispersion for mechanical strength.
3Strength
If Ti content is increased to form ultrafine particles, then mechanical characteristics are improved, but object-generated harmful factors increase due to formation of undesired intermetallic compound phases
Solution Approach 1:
The patent uses Ta, Nb, Hf, Zr, or Y elements as intermediary substances that interact with Ti to prevent the formation of undesired intermetallic compound phases. These intermediary elements have larger atomic radii and form stable compounds or modify the chemical environment, thereby suppressing the harmful phase formation while allowing Ti to contribute to ultrafine particle formation for mechanical strength enhancement.
Solution Approach 2:
The patent converts the potentially harmful effect of Ti (which can form undesired intermetallic compounds) into a beneficial effect by adding Ta/Nb/Hf/Zr/Y elements. These elements modify Ti's behavior, transforming it from a source of harmful phases into a contributor to beneficial ultrafine particle formation, thereby converting the harm into benefit for mechanical properties.
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 solution effectively suppresses the coarse growth or aggregation of undesired intermetallic phases, enhancing mechanical characteristics and corrosion resistance, enabling the alloy to perform well in harsh environments.
Implementation Method 1
ultrafine particles having an average particle size of 40 nm or less are dispersed and precipitated in matrix crystal
Implementation Method 2
stabilization of a mixed state caused by a negative increase in the mixing entropy term of the Gibbs free energy equation
Implementation Method 3
stabilization of a mixed state caused by a negative increase in the mixing entropy term of the Gibbs free energy equation
Implementation Method 4
improvement of mechanical characteristics by high lattice strain caused by a difference in size between constituent atoms
Implementation Method 5
improvement of corrosion resistance caused by a combined effect (also referred to as 'cocktail effect') of coexistence of multiple kinds of elements
Data Source
AI summary
Provided is an alloy material in which coarse growth or aggregation and precipitation of an undesired intermetallic compound phase can be suppressed, an alloy product formed of the alloy material, and a mechanical device including the alloy product. The alloy material according to the present invention includes: 5 at % or more and 40 at % or less of each of Co, Cr, Fe, and Ni; more than 0 at % and 8 at % or less of Mo; 1 at % or more and less than 8 at % of Ti; more than 0 at % and 4 at % or less of at least one kind of Ta or Nb; and a remainder consisting of unavoidable impurities, in which a total content of Ti and the at least one kind of Ta or Nb is 3 at % or more and 8 at % or less. In the alloy product formed of the alloy material, a total occupancy of η phase and Laves phase precipitates having a size of 1 μm or more is suppressed to be 5 area % or less.