NiTi 4D Printing With In-Situ Phase Transition Temperature Control
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Solution Overview
Problem
NiTi shape memory alloys face challenges in maintaining precise phase transition temperatures due to impurity introduction during smelting, low thermal conductivity, and poor processability, limiting their application in complex and precision parts, and current 4D printing methods lack effective in-situ regulation of functional properties.
Innovation Solution
A 4D printing method involving mixing NiTi alloy powder with nano-sized Ni powder, followed by discharge plasma ball milling to achieve metallurgical bonding, allowing precise control of the Ni/Ti atomic ratio and phase transition temperature through selective laser melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional smelting and casting methods are used to prepare NiTi alloys, then the alloys can be produced, but impurity elements (C and N) are introduced during processing, changing phase transition temperature and affecting functional properties
Solution Approach 1:
The invention changes the preparation method from traditional smelting to mechanical alloying via ball milling, fundamentally altering the processing parameters to avoid impurity introduction while maintaining production efficiency
Solution Approach 2:
The ball milling process is conducted in an inert atmosphere (argon or vacuum) to prevent contamination by carbon and nitrogen during alloy preparation, thereby maintaining precise phase transition temperature control
2Manufacturing precision
If 4D printing is used to prepare NiTi alloys, then complex and precision parts can be formed, but the high laser-melt pool temperature causes Ni atom volatilization, changing the Ni/Ti atomic ratio and phase transition temperature
Solution Approach 1:
The invention performs preliminary action by pre-alloying Ni and Ti powders through mechanical ball milling to create a homogeneous mixed powder with controlled composition before 4D printing, preventing compositional drift during laser processing
Solution Approach 2:
The invention uses composite powder consisting of mechanically alloyed Ni-Ti particles with controlled atomic ratios, combining the benefits of mechanical alloying (composition control) with 4D printing (complex geometry formation)
3Reliability
If NiTi shape memory alloys are used, then excellent biocompatibility and shape memory effect are achieved, but low thermal conductivity and poor processability reduce processing efficiency
Solution Approach 1:
The invention replaces traditional mechanical processing methods with additive manufacturing (4D printing), eliminating the need for difficult machining operations while maintaining the alloy's excellent biocompatibility and shape memory properties
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 enables the production of high-density NiTi alloys with uniform composition and properties, suitable for complex parts, enhancing their application in biomedical, aerospace, and other fields by achieving a single B2 austenite phase, high density, and superior superelasticity.
Implementation Method 1
discharge plasma ball milling to achieve metallurgical bonding
Implementation Method 2
discharge plasma ball mill for discharge treatment to promote the activation of powder activity, then adding nano-sized Ni powder... to realize the metallurgical bonding
Implementation Method 3
4D printing technology... can directly melt metal powder completely under the action of an external heating source
Implementation Method 4
selective laser melting
Data Source
AI summary
The present invention belongs to the field of additive manufacturing technology, and discloses a 4D printing method capable of in-situ regulating functional properties of nickel-titanium (NiTi) alloys and the application thereof. The method comprises the following steps: subjecting NiTi alloy bars to atomization milling to obtain NiTi alloy powder with a particle size of 15-53 μm, placing the NiTi alloy powder in a discharge plasma assisted ball mill for discharge treatment to promote the activation of powder activity, then adding nano-sized Ni powder with a particle size of 100-800 nm to obtain mixed powder, then continuing the discharge treatment to realize the metallurgical bonding between the NiTi alloy powder and the nano-sized Ni powder to obtain the modified powder, and finally using the additive manufacturing technology to prepare and form the modified powder into a functionalized NiTi alloy. The present invention achieves the metallurgical bonding between the nano-sized Ni powder and the large-sized spherical NiTi alloy powder by adding the nano-sized Ni powder in the process of discharge treatment, which is conducive to preparing a bulk alloy with uniform composition, structure and properties and the parts made therewith.