It is common for people to have memory, but it is amazing that metals also have memory! Why shape memory have “memory”?
First understand the memory principle and memory characteristics of shape memory alloys
The metal that has been processed into a certain shape at high temperature is rapidly cooled down, plastically deformed into another shape in the low-temperature phase state, and then heated to the high-temperature phase, that is, the temperature that can become a stable state, and the phenomenon of recovering to the shape before low-temperature plastic deformation through martensitic reverse phase transformation is called Shape Memory Effect. Metals with this effect are usually alloys composed of two or more metal elements, so they are called shape memory alloys. The shape memory effect is caused by martensitic phase transformation. The high-temperature phase and low-temperature phase involved in the martensitic phase transformation are called the parent phase and martensitic phase respectively. The driving force for shape recovery is the difference in free energy between the parent phase and the martensitic phase at the heating temperature.
Compared with other alloys, Shape Memory Alloys have excellent shape memory effect, excellent superelasticity, good damping properties, wear resistance and corrosion resistance. The elasticity of ordinary metal materials generally does not exceed 0.15%, while that of shape memory alloys is 20% or higher, so Shape Memory Alloys are also called superelastic alloys.
Powder parameters of nano nickel-titanium alloys produced by Hongwu Nano
Nano Nickel-Titanium Shape Memory Alloy, Nickel Titanium Alloy Nano Powders, particle size 70nm, ratio Ni:Ti=5:5, black solid powder, spherical morphology.
Characteristics of nano nickel-titanium alloys
As a new functional material integrating perception and drive, nano Nickel-Titanium Shape Memory Alloy is an important member of the intelligent material structure and has important theoretical and applied research value. Titanium-Nickel Shape Memory Alloy is a functional material with high strength, corrosion resistance, good biocompatibility, non-toxicity and medical application prospects. After deformation in the low-temperature phase, it only needs a slight temperature of 20 ~300℃ to restore the shape memorized by the parent phase. Its expansion rate is above 20%, fatigue life is up to 107 times, and damping characteristics are 10 times higher than ordinary springs. It has properties that ordinary metals cannot imagine. Data show that among the existing memory alloys, only Ni-Ti alloy can meet the requirements of chemical and biological reliability at the same time, and it is the only memory alloy currently used in medicine.
Application of nano Nickel-Titanium alloy
Because of its unique shape memory effect, biocompatibility, superelasticity and excellent wear resistance, it has been widely used in clinical and medical equipment, and has been widely used in stomatology, orthopedics, orthopedics, ENT, human body pipelines, minimally invasive interventional devices, artificial organs and tissues, coagulation filters, artificial hearts, correction wires, spinal orthopedic rods, patellar concentrators, etc.
As one of the key basic materials for intelligent materials, Shape Memory Alloy materials can be called ideal materials across the 21st century. Because it has special properties such as automatic action function and superelasticity, energy saving, and thermal sensitivity, it has not only attracted widespread attention from the industry, but now many domestic units and colleges and universities have applied nano nickel-titanium memory alloys to relevant fields and have achieved certain application results. China has been at the forefront of the world on Ni-Ti alloy in many aspects of medical applications.