3D Bimetal Lattice Metal for Isotropic Near-Zero Thermal Expansion
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Solution Overview
Problem
Existing materials and manufacturing methods struggle to achieve isotropic near-zero-expansion characteristics in three-dimensional lattice metals over a wide temperature range, particularly in aerospace applications, due to thermal stress and interface gaps in bimetallic structures.
Innovation Solution
A three-dimensional bimetallic lattice structure is designed with a truss structure embedded in a hexahedron, using Invar alloy and NiTi alloy with a transition region for metallurgical bonding, manufactured via laser coaxial powder feeding additive manufacturing, ensuring isotropic near-zero-expansion across various directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If bimetallic composite materials are used to achieve near-zero-expansion characteristic, then thermal expansion coefficient is reduced, but interface thermal matching problem causes failure due to thermal stress during extreme temperature changes
Solution Approach 1:
The patent applies local quality by creating a gradient structure where the thermal expansion coefficient transitions smoothly from one metal to another through controlled alloying elements. Instead of a sharp interface between two different metals, the composition gradually changes over a transition zone, allowing local properties to vary continuously and reduce thermal stress concentration at interfaces during temperature cycling.
Solution Approach 2:
The patent uses composite materials by combining multiple metal phases with different thermal expansion coefficients in a controlled gradient distribution. This composite structure leverages the near-zero expansion of certain phases while maintaining ductility and thermal stress resistance through the gradual composition transition, achieving both low thermal expansion and high reliability under thermal loading.
2Ease of manufacture
If fitting or assembly pattern is used for bimetallic materials, then manufacturing is simplified, but interface gaps affect the near-zero-expansion characteristic
Solution Approach 1:
The patent merges the manufacturing simplicity of assembly-based approaches with the performance benefits of continuous structures by using diffusion bonding or welding to create metallurgical bonds at interfaces. This eliminates gaps while maintaining the modular design advantages, ensuring continuous load transfer and preserving the near-zero-expansion characteristic without the complexity of fully integrated monolithic structures.
3Stability of the object's composition
If two-dimensional lattice structure is used, then near-zero-expansion characteristic is achieved in the plane, but practical application is hindered due to lack of three-dimensional isotropy
Solution Approach 1:
The patent applies dimensionality change by extending the near-zero-expansion lattice design from two dimensions to three dimensions. The unit cell structure is configured so that the gradient composition and lattice geometry work together in all spatial directions, achieving isotropic near-zero expansion behavior. This three-dimensional configuration allows the material to maintain dimensional stability regardless of the direction in which it is measured or applied.
4Ease of manufacture
If traditional additive manufacturing is used, then manufacturing flexibility is improved, but process constraint-based design limits functional integration
Solution Approach 1:
The patent inverts the traditional additive manufacturing approach by starting with a function-driven design rather than process-constrained design. The gradient composition and lattice geometry are optimized first to achieve the desired near-zero-expansion performance, and then the manufacturing process is selected and optimized to realize this design. This inversion allows for greater design freedom and functional integration while maintaining manufacturing feasibility through controlled additive manufacturing processes.
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 lattice metal exhibits a thermal expansion coefficient of less than 0.5×10−6 K−1 in a temperature range of −100° C. to 1000° C., with metallurgical bonding at interfaces, enhancing structural stability and isotropy.
Implementation Method 1
laser coaxial powder feeding additive manufacturing process
Implementation Method 2
manufactured via laser coaxial powder feeding additive manufacturing
Implementation Method 3
metallurgical bonding at the bimetallic interface
Implementation Method 4
thermal expansion coefficient is a core parameter to measure the dimensional change of a material when the temperature changes
Implementation Method 5
Near-zero-expansion material refers to a material that produces small geometric size change when subjected to temperature changes, it is insensitive to temperature change, and its thermal expansion coefficient is close to zero
Implementation Method 6
deformation of the lattice structure
Implementation Method 7
excessive temperature difference will easily lead to thermal stress deformation
Data Source
AI summary
Provided in the present invention are a near-zero expansion lattice metal based on additive manufacturing, and a preparation method and use therefor. The lattice metal has a three-dimensional bimetal lattice structure. The lattice metal is formed by expanding bimetal lattice cells. Each bimetallic lattice cell is of a three-dimensional structure having a truss structure embedded in a hexahedron, and has the capability of expanding in three spacial directions. A transition area is arranged at a connection position of the hexahedron and the truss structure, and the contour of the transition area is not larger than a pore-strut diameter of the cell. The hexahedron is a metal, and the truss structure is another metal. The transition area is a mixture of the two metals, and the ratio of linear expansion coefficients of the two metals is not lower than S. Interfaces of the two metals are metallurgically bonded without gaps.