
The single phase supersaturated Al-Mg (Al-mg) alloy is deformed. When the applied strain exceeds ~ 20GPa, the structure of the alloy sample is refined to nanometer scale, and approximately equiaxed randomly oriented nanocrystals are formed in the sample. The particle size distribution is uniform and the average particle size is 8nm (sample SC-8). A series of analyses and tests show that the supersaturated Mg atoms are uniformly distributed in the nanocrystalline structure, rather than aggregated or dispersed on GB like other Al-Mg alloys deformed at room temperature.
AI is a kind of metal with high diffusivity, and Mg is one of the most diffusive alloy elements. The team observed the diffusion behavior of supersaturated Al-Mg alloy with Schwarz crystal structure. The diffusion processes such as precipitation, grain coarsening and melting of intermetallic compounds were studied at different temperatures.
The structure of the sample evolves during annealing.
It is found that this minimum interfacial structure can not only reduce the atomic apparent transboundary diffusivity of supersaturated Al-Mg alloy by about 7 orders of magnitude, but also keep the alloy structure unchanged at temperatures higher than the melting point.
It is considered that the observation results in this supersaturated Al-Mg alloy are consistent with the team's previous observations in pure copper Schwarz crystal samples that inhibit coarsening to the melting point, which is a self-diffusion-controlled process.
The stability of lattice constant and grain size of the sample.
It is mentioned in this paper that the non-diffusion property of Schwarz crystal structure in metals is of great significance for understanding the basic diffusion process and solid-state transport kinetics at the interface, especially at high temperatures. On the other hand, Schwarz crystal seems to provide a strong barrier to prevent the diffusion of atoms in metals and substitute alloys and improve the stability of melting point temperature, which is much higher than that of traditional alloys.