Researchers at Kiel University in Germany have invented a new nickel-titanium-copper memory alloy, which can be deformed 10 million times without breaking, while the alloy materials usually break thousands of times. This new material will have wide application prospects in many fields such as microelectronics and optical devices, sensors, medical devices and so on.
As early as the 1960s, scientists invented NiTi memory alloys, which deform when heated and cooled, and quickly return to the shape determined in the initial mechanical processing. Most of the alloys we know change several thousand times in two lattice states and crack or even break. This is because there are more and more cryogenic phase (martensite) crystal structures in the high temperature phase (austenite) of metals, and incomplete transformation between the two phases will lead to alloy fracture, explained Kuang Te, an expert from Kiel University in Germany, in a paper published in the Journal Science.
The memory alloy unit invented by Kuang Te's team consists of 54 titanium atoms, 34 nickel atoms and 12 copper atoms. The researchers found that at 22 degrees Celsius to 87 degrees Celsius, the memory alloy can withstand tens of millions of times of deformation without cracking through high power electron microscopy and X-ray detection. The researchers can also see that under the microscope when martensite is completely transformed into austenite, two titanium and copper atoms are deposited in the lattice. The deposition of titanium and copper atoms forms the basic structure of the crystal in the two phases. They call this phenomenon epitaxial growth.
James, an expert at the University of Minnesota, developed a zinc, gold-copper memory alloy two years ago with similar properties. The alloy can withstand 16000 cold and hot deformation without cracking. The James team's invention was published in the journal Nature.
According to the Journal Science, the invention of Kiel University in Germany has greatly broadened the application of memory alloys. Electromagnetic couplers, temperature sensors, microelectronics and optical devices, information storage media, and artificial heart valves in the medical field have wide application potential. In addition, this kind of memory alloy can be used to convert heat energy from the outside world and the environment into electric energy, or to develop new cooling units.
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