Au-Cu-Al Shape-Memory Alloy for MRI Artifact Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional shape-memory alloys used in medical applications suffer from artifacts in magnetic resonance imaging (MRI) due to magnetization, which obstructs accurate diagnosis and treatment, and lack simultaneous biocompatibility, shape-memory characteristics, and artifactlessness.
Innovation Solution
A Ni-free Au-Cu-Al alloy with specific composition ranges (20-40 at% Cu, 15-30 at% Al, and balance Au) is developed, which exhibits a shape-memory effect at human body temperature and reduced bulk susceptibility, making it artifactless in magnetic environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ni-Ti-based shape-memory alloy is used to achieve shape-memory characteristics, then the alloy can return to its original shape after deformation, but it causes metal allergy and lacks biocompatibility
Solution Approach 1:
The patent changes the compositional parameters of the alloy by replacing Ni with Cu and Al, maintaining the shape-memory effect while eliminating the harmful Ni component. The specific composition range (Cu: 20-40 at%, Al: 15-30 at%) is optimized to achieve both biocompatibility and shape-memory characteristics.
Solution Approach 2:
The patent creates a composite alloy system combining Au, Cu, and Al elements. This composite material approach allows leveraging the biocompatibility of Au while incorporating Cu and Al to achieve the desired shape-memory effect and magnetic properties without Ni.
2Reliability
If conventional shape-memory alloy is used to achieve shape-memory effect, then the alloy can be deformed and return to original shape, but it creates artifacts in MRI images
Solution Approach 1:
The patent changes the magnetic parameters of the alloy by adjusting the Cu and Al content, which directly affects the bulk susceptibility. By controlling the composition within specific ranges, the alloy achieves low magnetic susceptibility and minimal MRI artifacts while maintaining shape-memory functionality.
3Temperature
If alloy composition is adjusted to reduce transformation temperature for superelasticity, then the alloy can function at body temperature, but it may increase magnetic susceptibility and create artifacts
Solution Approach 1:
The patent simultaneously optimizes multiple parameters including composition ratios of Cu and Al, heat treatment temperature, and cooling rate to achieve the desired transformation temperature while controlling magnetic susceptibility. The specific composition ranges and heat treatment conditions are carefully selected to balance these competing requirements.
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 alloy achieves biocompatibility, shape-memory characteristics, and artifactlessness, enabling its use in medical instruments like catheters and stents while maintaining suitable hardness and workability for processing.
Implementation Method 1
a shape-memory alloy is a metal alloy having such characteristics that at a temperature not lower than the transformation point, even when significantly deformed, the alloy can return to its the original shape
Implementation Method 2
An artifact is a phenomenon in which the metal materials constituting a medical instrument are magnetized by a magnetic environment, resulting in distortion in an MRI image
Data Source
AI summary
The present invention provides a shape-memory alloy including a Au—Cu—Al alloy having 20 at % or more and 40 at % or less Cu and 15 at % or more and 30 at % or less Al, with the balance being Au and inevitable impurities. The shape-memory alloy has a Vickers hardness of 360 Hv or less. The Au—Cu—Al alloy of the present invention is an alloy capable of developing both biocompatibility and a shape-memory effect, and further capable of achieving artifactlessness in a magnetic environment. The Au—Cu—Al alloy can be produced by heat-treating a clad material formed of a combination of a hollow material made of a Au—Cu alloy and a core material made of metallic Al at 500° C. or more and 700° C. or less.