Transformation-Induced Plasticity High-Entropy Alloy at Cryogenic Temperatures
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Solution Overview
Problem
Existing high-entropy alloys (HEAs) do not achieve optimal mechanical properties at cryogenic temperatures, particularly in terms of tensile strength and ductility, due to limitations in phase transformation at −196° C.
Innovation Solution
A transformation-induced plasticity high-entropy alloy with a composition of 10-35 at % Co, 3-15 at % Cr, 3-15 at % V, 35-48 at % Fe, and 0-25 at % Ni, primarily consisting of an FCC phase that transforms to a BCC phase at cryogenic temperatures, is developed, along with a preparation method involving homogenization, rolling, and annealing to maintain the FCC phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional single-phase FCC HEA composition is used, then phase stability is maintained, but mechanical properties at cryogenic temperature are insufficient
Solution Approach 1:
The patent modifies the compositional parameters of the HEA by replacing Mn with V and adjusting the Co content to 10-35 at%, which changes the phase transformation behavior to enable FCC-to-BCC transformation at cryogenic temperatures, thereby improving tensile strength while maintaining adequate phase stability
Solution Approach 2:
The patent utilizes phase transition as the core mechanism by designing the alloy composition to undergo FCC-to-BCC phase transformation during deformation at cryogenic temperatures, which enhances mechanical properties through transformation-induced plasticity while the initial FCC phase provides stability
2Strength
If Co—Cr—Fe—Mn—Ni based HEA is used, then deformation twins are generated at cryogenic temperature, but tensile strength and ductility are not optimized
Solution Approach 1:
The patent changes the compositional parameters by substituting V for Mn and optimizing Co content, which fundamentally alters the deformation mechanism from twin-based to transformation-induced plasticity, thereby optimizing both tensile strength and ductility at cryogenic temperatures
Solution Approach 2:
The patent employs phase transition from FCC to BCC structure during deformation as the primary mechanism for improving mechanical properties, replacing the deformation twin mechanism, which enables superior tensile strength and ductility optimization at cryogenic temperatures
3Strength
If FCC phase transformation to BCC phase is enabled at cryogenic temperature, then transformation-induced plasticity occurs, but phase stability may be compromised
Solution Approach 1:
The patent carefully adjusts compositional parameters within specific ranges (Co: 10-35 at%, Cr: 3-15 at%, V: 3-15 at%, Fe: 35-48 at%, Ni: 0-25 at%) to balance phase stability and transformation capability, ensuring the alloy maintains FCC phase stability while enabling controlled transformation to BCC phase for improved ductility
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 significantly improved tensile strength, ductility, and fracture properties at cryogenic temperatures, outperforming conventional single-phase HEAs with enhanced transformation-induced plasticity and phase stability.
Implementation Method 1
transformation-induced plasticity, in which at least part of the FCC phase changes to a BCC phase, occurs at a cryogenic temperature (−196° C.)
Implementation Method 2
a homogenization step, which includes heating and cooling for homogenizing the microstructure of a high-entropy alloy
Implementation Method 3
an annealing step, in which the rolled HEA is heated up to an FCC single-phase region, and then cooled at a cooling rate by which the FCC phase is able to be maintained
Data Source
AI summary
Present invention is about a transformation-induced plasticity high-entropy alloy which can provide improved mechanical properties compared to those obtained by conventional methods, due to the phase transformation occurring at the time of deformation at a cryogenic temperature. According to the present invention, the high-entropy alloy (HEA) includes 10-35 at % of Co, 3-15 at % of Cr, 3-15 at % of V, 35-48 at % of Fe, and 0-25 at % of Ni (exclusive of 25), and mainly consists of an FCC phase at room temperature, wherein transformation-induced plasticity, in which at least part of the FCC phase changes to a BCC phase, occurs at a cryogenic temperature (−196° C.)