Nickel Superalloy DED Microstructure Control With Zirconia Nanopowder
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Solution Overview
Problem
The directed energy deposition (DED) process in nickel-based superalloys leads to grain coarsening due to high heat input, affecting tensile properties, creep strength, and fracture toughness, and causing anisotropy in mechanical properties.
Innovation Solution
A method involving the use of a mixed powder comprising nickel-based superalloy powder and zirconia nano-powder, with controlled process variables, to establish a correlation between microstructure and internal variables, forming a target nickel-based superalloy DED structure with refined and uniform microstructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high heat input laser is used in directed energy deposition, then deposition efficiency is improved, but grain coarsening occurs leading to deteriorated mechanical properties
Solution Approach 1:
The patent applies parameter changes by optimizing laser power, scan speed, and powder feed rate to control heat input. By adjusting these parameters, the process achieves efficient deposition while maintaining fine grain structure through controlled cooling rates and thermal cycles, resolving the contradiction between deposition efficiency and grain size control
Solution Approach 2:
The patent employs periodic action through pulsed laser deposition and layer-by-layer building process. This periodic heating and cooling cycle allows for controlled solidification that refines grain structure while maintaining high deposition rates, addressing both productivity and mechanical property requirements
2Productivity
If high heat input laser is used in directed energy deposition, then deposition efficiency is improved, but grain coarsening occurs leading to deteriorated creep strength
Solution Approach 1:
The patent uses parameter changes to control thermal history during deposition. By optimizing laser parameters and build conditions, it achieves high deposition efficiency while maintaining fine grain structure that provides resistance to grain boundary sliding and dislocation creep, thereby preserving creep strength
Solution Approach 2:
The patent employs composite materials by adding zirconia nanoparticles to the nickel-based superalloy powder. This composite approach refines grain structure and creates dispersion strengthening that improves creep resistance while maintaining deposition efficiency through controlled processing parameters
3Productivity
If high heat input laser is used in directed energy deposition, then deposition efficiency is improved, but grain coarsening occurs causing anisotropy in mechanical properties
Solution Approach 1:
The patent applies parameter changes to control thermal gradients and solidification rates during deposition. By optimizing laser power, scan speed, and hatch spacing, it achieves uniform heat distribution that promotes equiaxed grain growth, reducing directional dependence and anisotropy in mechanical properties while maintaining high deposition efficiency
Solution Approach 2:
The patent introduces zirconia nanoparticles as an intermediary that acts as nucleation sites during solidification. These particles promote uniform grain nucleation throughout the melt pool, creating a more isotropic grain structure that reduces mechanical property anisotropy while allowing efficient deposition
4Device complexity
If conventional directed energy deposition is used, then simple process is maintained, but microstructure control is insufficient leading to coarse grains
Solution Approach 1:
The patent uses composite materials by incorporating zirconia nanoparticles into the nickel-based superalloy powder. This addition provides nucleation sites that refine grain structure during solidification, achieving microstructural control without significantly complicating the deposition process
Solution Approach 2:
The patent applies parameter changes to laser power, scan speed, and powder feed rate to control thermal history and solidification rate. These adjustments enable microstructure refinement through controlled cooling rates while maintaining the simplicity of the directed energy deposition 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
Achieves microstructural refinement, uniformity, and high hardness in nickel-based superalloy DED structures, improving tensile properties and reducing anisotropy.
Implementation Method 1
forming a nickel-based superalloy directed energy deposition structure by performing directed energy deposition with the mixed powder using a laser
Implementation Method 2
melting the base material and the metal powder simultaneously
Implementation Method 3
melting and solidifying the metal powder to form a two-dimensional metal layer
Data Source
AI summary
Provided a method of controlling microstructure of nickel-based superalloy directed energy deposition structure to obtain microstructural refinement, uniformity, and high hardness. The method of controlling microstructure of directed energy deposition structure includes, providing a mixed powder comprising a nickel-based superalloy powder and a zirconia nano-powder; forming a nickel-based superalloy directed energy deposition structure by performing directed energy deposition with the mixed powder using a laser with a process variable; and establishing a correlation between microstructure and an internal variable of the nickel-based superalloy directed energy deposition structure.