Hefei Research Institute made progress in the development of highly stable metal nanomultilayers

Recently, the Nuclear Materials Research Group of the Institute of Solid State Physics, Chinese Academy of Sciences, Institute of Solid State Physics, Hefei Institute of Physics, based on the interface engineering design, adopted a large plastic deformation method to successfully prepare high interface Cu with high strength and high thermal stability. /Ta nano-multilayer film bulk. Related research results were published in Acta Materialia 2016, 110, 341-351.

Nanostructured materials, because of their high strength and rich interface, are considered ideal candidates for next-generation nuclear power devices. However, the traditional nanostructured materials (such as nanocrystalline materials) are not stable in structure and properties under extreme conditions such as high temperature and strong irradiation. Therefore, preparation of nanostructured materials with high strength and high stability at the same time has always been a material research. problem. Studies have shown that nano-multilayers composed of completely immiscible metals have high strength, high thermal stability, and excellent radiation resistance, but their preparation methods rely mainly on bottom-up physical or chemical methods. Because of its low production efficiency, it cannot meet the needs of industrial applications.

In response to the above problems, the research team of the Institute of Solids has effectively overcome the material accumulation by using a combination of orthogonal cumulative roll bonding (CARB) and intermediate annealing processes based on the large plastic deformation accumulative roll bonding (ARB) method. In the phenomenon of plastic instability and edge cracking during the process of stack rolling, a high-interface Cu/Ta nano multilayer film block with a layer number of 12288 layers and a minimum single-layer film thickness of 50 nm was successfully prepared for the first time. The microstructure shows that the layered structure is continuous and the Cu/Ta interface is straight and clear. The mechanical property test results show that the strength of the Cu/Ta nano-multilayer film reaches 5 times the initial raw material. More importantly, this material also has very good high-temperature thermal stability. After annealing at 500°C for one hour, the hardness does not change. After annealing at 600°C for one hour, the hardness only decreased by 6.6% (see figure). The successful preparation of this high-strength, high-heat-stability material provides new ideas for the design of materials under extreme conditions, which lays the foundation for further research on nano-multilayers of Cu/V, Cu/W, Cr/W and other bulk materials. .

The study was funded by the National Natural Science Foundation of China and the Natural Science Foundation of Anhui Province.

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