Domestic researchers have found a new way to make metals stronger and more flexible.
Professor Kim Hyung-seop and researchers from Pohang University of Science and Technology (POSTECH) noted on the 4th that they enhanced both the strength and ductility of metals using a 'plasma nitriding method' that penetrates nitrogen into the metal surface. The research results were published in the mechanical engineering journal International Journal of Plasticity in December of last year.
The research team developed a plasma nitriding technology that applies a nitride layer with a thickness of ㎚ (nanometer, one billionth of a meter) to the metal surface. This technology coats metals with a special protective layer, similar to applying a protective film on a smartphone.
Existing plasma technology was difficult to apply to metals with complex shapes. The technology developed by the researchers can perform nitriding in a short time at low pressure and appropriate temperatures, creating a thin and uniform protective layer on the metal surface, similar to a liquid crystal protective film.
The research team conducted experiments on 'high-entropy alloys,' which are actively studied recently, and 'stainless steel 304', which is widely used in industry. As a result, a nitride layer of approximately 300㎚ thickness was formed on the metal surface, but the fundamental characteristics of materials such as basic structure and crystallography remained unchanged. At the same time, the maximum load that the material can withstand before permanent deformation or breakage, known as 'tensile strength,' increased by 74.6 MPa (a unit that indicates pressure). The maximum amount of uniform deformation the material can undergo, known as 'uniform elongation rate,' rose by 7.9%, successfully enhancing both strength and ductility.
Professor Kim Hyung-seop said, 'The new plasma nitriding method provides uniform performance without the early fracture of materials, unlike existing technologies, and can be immediately applied in industry without additional processing.' He added, 'This research will lead to the emergence of safer metal processing methods in the aerospace and automotive industries.'
References
International Journal of Plasticity (2024), DOI: https://doi.org/10.1016/j.ijplas.2024.104235