High Entropy Alloy Wear Resistance via Dual FCC Phase Design
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Solution Overview
Problem
Current high wear-resistant alloys like tool steels, manganese steels, and white cast iron exhibit poor corrosion resistance, making them unsuitable for hazardous environments, and they are prone to cracking during hardening heat treatment due to low ductility and high cooling speeds.
Innovation Solution
Development of high entropy alloys with a dual microstructure comprising two FCC phases, which provide a balance of high hardness, wear resistance, and corrosion resistance through a specific composition and heat treatment process, particularly increasing the Si content to enhance hardness and phase ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional high wear-resistant alloys (tool steels, manganese steels, white cast iron) are used to achieve high hardness and wear resistance, then wear resistance is improved, but corrosion resistance deteriorates
Solution Approach 1:
The invention changes the compositional parameters by introducing high entropy alloying elements (Cr, Mn, Si, Ni, Fe) in specific proportions, where Si content is particularly optimized (4-20 wt.%) to achieve both high wear resistance and good corrosion resistance simultaneously, moving away from conventional alloy compositions
Solution Approach 2:
The invention creates a composite microstructure consisting of two distinct FCC phases (dark grey phase and light grey phase) with different chemical compositions, where the dark grey phase provides wear resistance and the light grey phase provides corrosion resistance, achieving both properties in a single material
2Strength
If hardening heat treatment is applied to conventional alloys to increase hardness, then hardness is improved, but ductility deteriorates causing cracks
Solution Approach 1:
The invention changes the microstructural parameters by creating a dual-phase FCC structure that maintains ductility during hardening, allowing the alloy to withstand the thermal stresses of hardening heat treatment without cracking, unlike conventional single-phase alloys
Solution Approach 2:
The dual-phase microstructure acts as a cushioning mechanism before hardening heat treatment, where the softer light grey phase can accommodate thermal stresses and prevent crack initiation during the subsequent hardening process
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 entropy alloys demonstrate significantly improved hardness and wear resistance while maintaining good corrosion resistance, effectively withstanding extreme conditions including corrosive environments, and avoiding cracking during heat treatment.
Implementation Method 1
The high entropy alloy may be submitted to a hardening heat treatment by which its hardness is improved proportionally to the quantity of one of the main chemical elements (Si)
Implementation Method 2
High entropy alloys are well known alloys with solid solution hardening mechanism of different elements in the range of near to equiatomic proportion
Implementation Method 3
The high entropy alloys of the invention show advantageously high hardness and high wear resistance... The high entropy alloy as cast herein disclosed... comprises a dual microstructure conformed by two different FCC (Face Center Cubic) phases
Data Source
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AI summary
The present invention discloses high entropy alloys that consist of the following composition, wherein the percentages are expressed by weight with respect to the total weight of the alloy: 5-20wt.% Cr, 10-25wt.% Mn, 0.3-20wt.% Si, 0.2-6wt.% Fe and the balance Ni and unavoidable impurities. The invention also discloses a process for manufacturing these high entropy alloys with high hardness values. The invention also comprises submitting the alloys to a thermal treatment and achieving an improved hardness and very good corrosion resistance. Finally, the invention refers to the uses of these alloys for manufacturing parts for use for example cutting tools, high temperature heat exchange applications and high wear resistance components in machinery for construction and mining.