High Entropy Alloy Homogeneity via Additive Manufacturing
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Solution Overview
Problem
High entropy alloys (HEAs) face challenges in achieving uniform microstructure and composition due to element segregation during casting, leading to inconsistent characteristics and difficulty in shaping due to their hardness and resistance to deformation.
Innovation Solution
A high entropy alloy article composed of Co, Cr, Fe, Ni, and Ti, with optional Mo, manufactured using a powder-based additive manufacturing method, which includes mixing and melting raw materials, atomizing to form a powder, and using additive manufacturing to create a desired shape, resulting in a homogeneous alloy with acicular crystals dispersed in a matrix phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If casting method is used to produce high entropy alloy, then production efficiency is improved, but element segregation and microstructure unevenness occur leading to poor homogeneity
Solution Approach 1:
The patent applies preliminary action by pre-mixing the five main metallic elements (Co, Cr, Fe, Ni, Ti) in precise atomic percentages (each 5-35 at%) and optional Mo (0-8 at%) before melting. This pre-mixing ensures uniform distribution of elements throughout the molten alloy, preventing segregation during subsequent casting or additive manufacturing processes, and achieving homogeneous microstructure and composition in the final alloy article.
2Strength
If high entropy alloy is produced with significant hardness, then mechanical strength is improved, but ease of mechanical processing and plastic deformation deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the atomic percentages of constituent elements (Co: 5-35at%, Cr: 5-35at%, Fe: 5-35at%, Ni: 5-35at%, Ti: 5-35at%, Mo: 0-8at%) to achieve the optimal balance between mechanical strength and processability. This compositional parameter control, combined with the specific microstructure featuring acicular intermetallic compound crystals dispersed in the matrix, enables the alloy to possess significant hardness and strength while maintaining sufficient ductility for practical manufacturing and deformation processing.
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 method produces HEA articles with excellent homogeneity, shape controllability, significant mechanical strength, and high corrosion resistance, enabling the creation of complex shapes like impellers for fluid machines with improved durability.
Implementation Method 1
a local melting and solidified layer forming substep to form an additive manufactured object with a desired shape by locally heating and melting the metal powder
Implementation Method 2
atomizing to form a high entropy alloy powder from the molten metal
Data Source
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Figure 3A~3B
AI summary
An object of the invention is to provide: an HEA article that has excellent homogeneity in the alloy composition and microstructure as well as significant shape controllability, using an HEA with significant mechanical strength and high corrosion resistance; a method for manufacturing the HEA article; and a product using the HEA article. There is provided an HEA article comprising: Co, Cr, Fe, Ni, and Ti elements, each element in content of 5 to 35 atomic %; more than 0 atomic % to 8 atomic % of Mo %; and remainder substances of unavoidable impurities.