Dual-Phase High-Entropy Alloy Ti Addition Strength
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Solution Overview
Problem
Traditional single-phase high-entropy alloys like FeCoNiCrMn exhibit limited yield strength and elongation, restricting their applications due to inability to be strengthened by heat treatment and significant reduction in elongation through traditional work hardening methods.
Innovation Solution
A high-plasticity dual-phase high-entropy alloy (HEA) with a chemical formula of (FeCoNiCr)100-xTix, where x ranges from 2.0 to 2.8, is developed. This alloy includes a FeCoNiCr matrix with added Ti, which provides solid solution strengthening and forms Ni3Ti, enhancing strength without compromising plasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional work hardening is applied to single-phase HEA, then strength is improved, but elongation is greatly reduced
Solution Approach 1:
The invention introduces a dual-phase structure (BCC and FCC phases) through controlled addition of Ti element and specific melting processes. The BCC phase provides strength while the FCC phase maintains ductility, allowing the alloy to achieve high yield strength (400 MPa) without significantly compromising elongation (62%). This phase transition approach fundamentally changes the strengthening mechanism from work hardening to phase-based strengthening.
Solution Approach 2:
The invention creates a composite microstructure at the phase level within the HEA, combining BCC and FCC phases with distinct properties. The BCC phase (providing strength) and FCC phase (providing ductility) coexist and interact, enabling simultaneous achievement of high strength and high elongation without relying on traditional work hardening that would sacrifice ductility.
2Strength
If heat treatment is applied to single-phase HEA, then strengthening is achieved, but the alloy lacks response to heat treatment due to single-phase structure
Solution Approach 1:
By introducing Ti element to create a dual-phase structure, the alloy gains heat treatment responsiveness. The BCC and FCC phases can be controlled and adjusted through heat treatment processes, allowing for post-processing strengthening and property optimization that was impossible with the single-phase structure.
3Strength
If dispersed nano-second phase strengthening is applied, then strength is improved, but equipment requirements become high and industrial application becomes difficult
Solution Approach 1:
The invention changes the compositional parameter by adding Ti element (2.0-2.8 at%) to induce dual-phase formation during conventional melting processes. This approach achieves strengthening through composition control rather than complex nano-scale processing, making the method suitable for industrial application with standard equipment.
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 high-plasticity dual-phase HEA achieves a maximum tensile strength of 710 MPa, a yield strength of 400 MPa, and an elongation of 62%, ensuring excellent plasticity and high strength, thus overcoming the limitations of traditional single-phase HEAs.
Implementation Method 1
Ti is quite different from the matrix elements in an atomic radius, resulting in lattice distortion to improve the yield strength and tensile strength of the alloy
Implementation Method 2
the added Ti exerts an effect of solid solution strengthening, and on the other hand it could also combine with Ni in the matrix to form Ni3Ti
Implementation Method 3
a desirable coherent interaction between dual phases of the alloy further ensures excellent plasticity of the alloy
Data Source
AI summary
Provided are a high-plasticity dual-phase high-entropy alloy (HEA) and a preparation method thereof. The high-plasticity dual-phase HEA has a chemical formula as shown in Formula I: (FeCoNiCr)100-xTix (Formula I), in which, x is in a range of 2.0 to 2.8. A method for preparing the high-plasticity dual-phase HEA is also provided.