The development of high-performance metal materials

Xu Wei, Zhang Bo, Li Xiuyan and Lu Ke, postdoctoral fellow of nanomaterials Science Studio, Shenyang National Research Center for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, found that the confined crystal structure can significantly reduce the high temperature atomic diffusion rate in al-mg alloy. At the equilibrium melting temperature, the apparent intergranular diffusion rate of the confined crystal structure is about 7 orders of magnitude lower than that of the grain boundary diffusion of the materials with the same composition.

This discovery not only reveals a new atomic diffusion behavior of confined crystal structure, but also shows that the atomic diffusion rate of metal materials at high temperature can be greatly reduced by using this new metastable structure, which opens a new way for the development of high performance and high thermal stability metal materials.

Atomic diffusion is a basic process to control the structure and properties of materials.

Using the high diffusion rate of metal, the structure and properties of metal materials can be greatly adjusted at low temperature, so as to obtain good comprehensive properties. However, the high diffusion rate will also lead to the structural instability of metal materials at high temperature, and many metals will appear the loss of excellent properties and strength.

In 2020, the team discovered a new type of metastable structure called restricted crystal structure.Subsequently, the research team used the self-developed low temperature plastic deformation technology to refine the grain size of the susaturation Al-15%Mg alloy wafer to less than 10 nanometers, and successfully obtained the restricted crystal structure. Using this structure, the evolution of three atomic diffusion-controlled structures during the heating process of the alloy was systematically studied.

The results show that the evolution of the three structures can be effectively inhibited by the confined crystal structure at high temperature close to the melting point of the alloy, and even the melting temperature of the alloy is increased by 69K compared with the equilibrium melting point, showing an ultra-low atomic diffusion rate.