We have to make our own big planes, high-speed rails, battleships, which kind of material is the most suitable? What kind of configuration is the safest? What causes the problem? To study these problems, we must rely on the ability to reveal the state of atoms and molecules. 'Neutron scattering technology'.
In 2015, the Institute of Nuclear Physics and Chemistry of the Chinese Academy of Engineering Physics (CAS) developed the first neutron science platform for scientific research and engineering applications in China, becoming the most important tool for studying the structure and dynamics of materials. I. What has been the role of this scientific platform that carries the dreams of the older generation of scientists for three years of operation? A few days ago, a reporter from Science and Technology Daily conducted an interview.
Answer 'What are the atoms doing?'
The experimental method for measuring the microstructure of a material using neutrons is called neutron scattering. It not only tells us where 'atoms are' but also tells us what atoms are doing. This is also the current determination of the microstructure of materials, non-destructive testing of remnants of materials. Stress, the only tool for direct observation of the material flux lattice. Currently, only reactor and spallation neutron sources in the world can generate neutron beams for neutron scattering experiments where the reactor neutron source is in a continuous steady state. The beamlet, spalled neutron source produces a pulsed neutron source.
Unlike the Chinese spalled neutron source that was just announced in Guangdong, the Neutron Science Platform of the Chinese Academy of Sciences, relying on the first full-power operation in 2011, has inherently good safety, and has a large experimental space in China's Mianyang Research Reactor and the country’s first cold Sub-source establishment, with 'Kirin' 'Phoenix' and other six spectrometers.
According to the person in charge of the platform, the neutron science platform can be found in important research fields such as organic photoelectric materials, polymer physics, flammable ice research, and domestic engine development in the past three years. 'The platform was first realized in a neutron way, quickly and accurately. Observe the solution aggregation behavior of the material molecules; Obtain the accurate data of the three-dimensional residual stress distribution of the engine disk with a diameter of 1100 mm and a weight of 50 kg in a specific area for the first time, and become one of the few laboratories in the world with research conditions for flammable ice hydrate. '
'Perspective' engine disk
Aerospace, high-speed alloy parts such as turbine disks and blades of aerospace engines require high temperatures of 600 to 1,200 degrees Celsius, long-term operation under certain stress, and are resistant to oxidation and corrosion. Only accurate measurement of their stress distribution values can optimize their manufacturing. Process.
'And to complete the distribution of three-dimensional residual stress in high-temperature alloy materials without destroying the structure of the components, the residual stress analysis of neutrons is the only method. 'The members of the scientific research team said that the micromechanical behavior of materials is measured, code name' The Unicorn's neutron stress spectrometer has been used in China's aerospace field for the first time. The team obtained the first accurate data of three-dimensional residual stress distribution in a specific area of an engine disk with a diameter of 1100 mm and a weight of 50 kg for the first time in the country. The analysis and fitting of internal residual stresses in the aircraft engine's turbine disk, blades and aircraft skin were completed.
The conditions for the study of flammable ice are very harsh, and the high-voltage neutron diffraction spectrometer 'Phoenix' used for crystal structure and phase change measurement in the platform possesses such capabilities. At present, the research team has built a composite of high pressure low temperature hydrates. Characterization of the experimental system has become one of the few laboratories in the world with research conditions for combustible ice hydrates.
In order to meet various fields and carry out neutron scattering research under various extreme conditions, in the past three years, the research team of the Chinese Academy of Sciences researched and developed a variety of in-situ environmental devices, as well as goniometers, electromagnets, and shear rheology. Instruments and other commonly used in situ environmental equipment platform.