Recently, the latest research results of Chongqing University in the journal Nature. On February 24, Professor Huang Xiaoxu of Chongqing University’s School of Materials and the chen Bin Research Institute team of Beijing High Pressure Science Research Center jointly published the title “High pressure in ultrafine-grained metals” in nature. (High-pressure reinforcement of ultrafine crystal metals), the results of which are an important development in the field of materials science.
The field of materialscience has long been pursuing the goal of developing materials with higher strength, wherein the characteristics of the micro-organization of the material affect the strength of the material to some extent – generally speaking, the smaller the micro-organizational unit (called “grain”) of the material, the higher the intensity.
However, over the past 20 years, there have been numerous computer simulation studies and related experimental studies that show that when the grain is less than a critical size (about 10 to 15 nanometers), the grain is further refined and the strength of the material does not rise or fall. Scientists believe the phenomenon may be due to the plastic deformation of the interface between grains in nanomaterials.
However, due to equipment limitations, the performance of materials with grain sizes of less than 15 nanometers cannot be accurately measured, so scientists have a problem: how to build the most direct and reliable experimental data between material strength and grain size for nanometals with finer grain sizes.
Now, Professor Huang Xiaoxu’s team and Chen Bin’s research team have found a solution. Their research is the first to introduce high-pressure experimental methods in the field of geosciences into nanomaterials research, creatively solving previous technical challenges, and for the first time reported the reinforcement of nanopure metals with grain sizes of less than 10 nanometers.
By studying the high-pressure deformation of nanopure metal nickel, it was found that the strength of the material continued to increase with the decrease in grain size, and to the researchers’ surprise, the smaller the grain size, the more significant the reinforcement effect. In the smallest grain size (3 nm) sample studied, a high yield strength of 4.2 GPa was obtained, 10 times higher than conventional commercial pure nickel strength.
In addition, plastic computational simulation and transmission electron microscope analysis showed that high-pressure deformation inhibited the crystal boundary sliding in nanomaterials and promoted the storage of crystal defects (misalignment) that act a role in reinforcement, resulting in high-pressure fine crystal reinforcement.
All in all, this discovery will further refresh the understanding of the phenomenon of critical grain size in nanomaterial reinforcement, and re-stimulate the exploration of super-metallic metals through the regulation of the grain size and microstructure of the material.