Nitinol Remelting via Laser Capillary and Rapid Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing Nitinol semi-finished products fail to effectively control the formation and distribution of inclusions, leading to undesirable phases that negatively impact material properties such as fatigue behavior and corrosion resistance, particularly in medical implants where miniaturization and quality requirements are increasing.
Innovation Solution
A method involving high-energy, focused radiation to create a melting capillary within the material, combined with a heat sink for rapid cooling, allowing for selective remelting and alloying that suppresses the formation of inclusions by achieving a high cooling rate through localized heating and cooling, resulting in a homogeneous structure without precipitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional vacuum melting technologies are used, then high-purity raw materials can be processed, but inclusions still form and negatively impact material properties
Solution Approach 1:
The invention changes the thermal parameters by implementing rapid heating to melt the material followed by rapid cooling at rates exceeding 10^6 K/s. This parameter change transforms the solidification process, preventing inclusion formation by quickly passing through the temperature range where precipitates would form, thus resolving the contradiction between maintaining high purity and eliminating inclusions
Solution Approach 2:
The invention utilizes phase transitions by rapidly heating the material from solid to liquid state and then rapidly cooling it back to solid. This controlled phase transition process, particularly the rapid solidification stage, prevents the formation of unwanted precipitates and inclusions during the phase change, thereby improving material reliability while eliminating harmful factors
2Object-generated harmful factors
If rapid cooling is applied to suppress inclusion formation, then inclusion size and number are reduced, but the cooling rate must be extremely high to be effective
Solution Approach 1:
The invention replaces conventional mechanical cooling systems with a laser-based heating system that enables controlled rapid phase transitions. The laser provides extremely high energy density for rapid heating, and the subsequent rapid cooling is achieved through controlled heat dissipation, eliminating the need for complex mechanical cooling apparatus while achieving the required cooling rates exceeding 10^6 K/s
Solution Approach 2:
The invention employs periodic action through pulsed laser heating followed by rapid cooling cycles. This periodic heating and cooling process allows precise control over the thermal history of the material, enabling multiple passes through the melting and solidification ranges to ensure complete suppression of inclusion formation while maintaining the required extreme cooling rates
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 significantly reduces the size and number of inclusions, enhancing the fatigue strength and corrosion resistance of Nitinol products, enabling the production of high-quality semi-finished materials suitable for advanced medical applications.
Implementation Method 1
The material is melted selectively locally in a melting capillary in the material volume by means of high-energy, focused radiation
Implementation Method 2
high-energy, focused radiation to create a melting capillary within the material
Implementation Method 3
the heat dissipation from the melting capillary is effected via the cold, non-remelted material volume adjacent to the melting capillary
Implementation Method 4
solidification of the melt is effected by means of a cooling device at a high cooling rate
Implementation Method 5
rapid solidification/quenching of the molten material is enforced by means of a cooled heat sink
Data Source
AI summary
A method and an apparatus for producing metallic semi-finished products by means of remelting and/or remelt-alloying. Here, the material is melted selectively locally in a melting capillary in the material volume by means of high-energy, focused radiation, the melting capillary is moved through the material and the material is cooled down at a high cooling rate by means of a cooled heat sink, which is located close to the melting capillary and coupled to the material in a well heat-conductive manner.