Ni-Base Superalloy Composition for Crack-Resistant SLM
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Solution Overview
Problem
Ni-based superalloys with high γ′ (Gamma Prime) phase content are highly susceptible to hot cracking during Selective Laser Melting (SLM), limiting their industrialization, especially in high-temperature applications like the gas turbine industry, as existing solutions either fail to completely prevent cracking or are economically unviable.
Innovation Solution
A Ni-based superalloy composition with increased Hafnium (Hf) content and controlled Hf/C ratio, along with a protective atmosphere during SLM processing, to form low-melting eutectics and reduce hot cracking susceptibility by enhancing the backfilling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high γ′ phase content is used to improve high-temperature strength, then mechanical strength is improved, but hot cracking susceptibility increases during SLM processing
Solution Approach 1:
The invention changes the chemical composition parameters of the Ni-based superalloy by precisely controlling the content of alloying elements (Al: 5-7 wt.%, Ti: 2-4 wt.%, Hf: 0.5-2 wt.%, C: 0.05-0.2 wt.%, and other elements within specified ranges) to optimize the γ/γ′ phase structure. This parameter optimization reduces hot cracking susceptibility during SLM while maintaining high-temperature strength through controlled γ′ phase precipitation.
Solution Approach 2:
The invention creates a composite microstructure consisting of γ matrix and γ′ precipitates with optimized composition and distribution. The controlled alloying elements form a complex multi-phase composite structure where Hf, Ti, and Al combine to create a microstructure that simultaneously provides high-temperature strength and crack resistance during additive manufacturing.
2Reliability
If processing temperature is increased to reduce hot cracking, then hot cracking susceptibility is reduced, but equipment complexity and oxidation risk increase
Solution Approach 1:
Instead of increasing processing temperature to reduce hot cracking, the invention changes the material composition parameters (optimizing Al, Ti, Hf, and C content ratios) to inherently reduce hot cracking susceptibility. This allows processing at conventional temperatures without requiring complex equipment redesign or vacuum/protective atmosphere systems.
Solution Approach 2:
The invention converts the typically harmful low-melting eutectic phases into a beneficial backfilling mechanism. The controlled presence of elements forming low-melting eutectics (particularly Hf-C and Ti-Al systems) enables liquid phase backfilling of cracks during SLM processing, transforming what is normally a cracking-promoting factor into a crack-healing mechanism.
3Reliability
If conventional alloy compositions are used to maintain material cost, then material cost is controlled, but hot cracking susceptibility remains high
Solution Approach 1:
The invention optimizes the composition parameters of conventional alloying elements (Al, Ti, Hf, C, Cr, Co, W, Mo, Ta, Nb, Zr, B) within specific ranges rather than using expensive rare earth elements. This parameter optimization achieves crack-free SLM processing while maintaining cost-effectiveness by using commercially available alloys with controlled compositions.
Solution Approach 2:
The invention uses small, controlled amounts of inexpensive elements (particularly C at 0.05-0.2 wt.%, and B at 0.01-0.05 wt.%) that form low-melting eutectics to enable crack backfilling. These small additions of cheap elements provide significant crack resistance without substantially increasing material cost.
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
Significantly reduces hot cracking susceptibility during SLM processing, enabling the production of crack-free parts with improved surface quality and geometric freedom, while maintaining mechanical properties and reducing material costs.
Implementation Method 1
increased Hafnium (Hf) content and controlled Hf/C ratio, to form low-melting eutectics and reduce hot cracking susceptibility
Implementation Method 2
cracking susceptibility during an AM process is considerably reduced by controlling the amount of elements that form low-melting eutectics
Implementation Method 3
Selective laser melting of γ′ (Gamma Prime) Ni3 (Al, Ti) hardened Ni-based superalloys
Implementation Method 4
Selective laser melting (SLM) or electron beam melting (EBM)
Implementation Method 5
which might inhibit the recyclability and thus increases material costs. Additionally, a strong sintering of the powder is expected at such high temperatures
Data Source
AI summary
A Ni-based superalloy composition to be used for powder-based additive manufacturing (AM) technology, such as selective laser melting (SLM) or electron beam melting (EBM). The cracking susceptibility during an AM process is considerably reduced by controlling the amount of elements, especially Hf, that form low-melting eutectics.