Sintered Shape Memory Alloy via Fused Filament Fabrication
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Solution Overview
Problem
Additive manufacturing of metal or alloy components, particularly shape memory alloys, faces challenges such as grain structure alteration due to melting, residual powder residue, and cracking issues due to thermal gradients, which are not effectively addressed by existing techniques like powder bed fusion.
Innovation Solution
The method involves fused filament fabrication using a filament with a sacrificial binder and a shape memory alloy powder, where the binder is removed and the component is sintered to join SMA particles, avoiding melting and controlling microstructure, thus reducing crack propensity and residual powder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If powder bed fusion is used to manufacture shape memory alloy components, then metal components can be produced, but grain structure is altered due to melting
Solution Approach 1:
The invention changes the processing parameters from melting temperatures to sintering temperatures. By using a binder to hold powder particles together and then sintering at temperatures below the melting point of the shape memory alloy, the grain structure is preserved while still achieving component formation and bonding.
Solution Approach 2:
The invention introduces a binder as an intermediary material that temporarily holds the shape memory alloy powder particles together during fabrication. This binder allows the powder to be deposited and shaped without requiring direct melting of the metal particles, thus preserving the grain structure while enabling additive manufacturing.
2Ease of manufacture
If powder bed fusion is used to manufacture shape memory alloy components, then metal components can be produced, but residual powder residue remains
Solution Approach 1:
The invention extracts and removes the binder material after the component structure is formed. This extraction process eliminates residual powder residue by dissolving or decomposing the binder, leaving behind only the consolidated shape memory alloy particles with clean surfaces and no remaining binding material.
Solution Approach 2:
The invention uses temperature and chemical parameter changes to selectively remove the binder. By controlling the sintering temperature and/or applying chemical treatments, the binder is removed while the shape memory alloy particles remain intact, achieving complete residue elimination.
3Ease of manufacture
If powder bed fusion is used to manufacture shape memory alloy components, then metal components can be produced, but cracking occurs due to thermal gradients
Solution Approach 1:
The invention changes the thermal processing parameters from high-temperature melting to lower-temperature sintering. This parameter change reduces the thermal gradients and thermal stresses that cause cracking, while still achieving sufficient bonding between particles through the sintering process.
Solution Approach 2:
The binder acts as a thermal intermediary that distributes heat more uniformly throughout the powder bed during processing. This reduces localized thermal gradients and prevents the formation of cracks that would occur with direct laser melting of metal particles.
4Shape
If conventional additive manufacturing is used, then complex three-dimensional structures can be formed, but high-melt temperature alloys cannot be effectively processed
Solution Approach 1:
The binder serves as a thermal intermediary that enables the processing of high-melt temperature alloys. By holding the alloy particles together through the binder rather than requiring the alloy itself to be molten, the invention can form complex geometries while maintaining compatibility with high-temperature materials that would otherwise be difficult to process additively.
Solution Approach 2:
The invention changes the processing temperature regime from above-melting-point to below-melting-point sintering. This parameter change enables the use of high-melt temperature alloys in additive manufacturing by forming complex structures at temperatures where the alloy remains solid, avoiding the need to melt refractory metals and alloys.
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
This approach enables the formation of components with desired properties, complex geometries, and reduced porosity, while allowing for the use of high-melt temperature alloys and dissimilar metals, thereby overcoming the limitations of existing methods.
Implementation Method 1
removing substantially all the sacrificial binder from the fused filament fabricated component to leave an unsintered component
Implementation Method 2
sintering the unsintered component to join particles of the SMA and form an SMA component
Data Source
AI summary
A method may include fused filament fabricating a fused filament fabricated component by delivering a softened filament to selected locations at or adjacent to a build surface. The softened filament may include a sacrificial binder and a powder including a shape memory alloy (SMA). The method also may include removing substantially all the sacrificial binder from the fused filament fabricated component to leave an unsintered component; and sintering the unsintered component to join particles of the SMA and form an SMA component.