AHUT Reveals Rare Earth Nitriding Mechanism

Anhui University of Technology (AHUT) has revealed rare earth nitriding mechanism recently. Through first-principles studies of the effects of rare metal elements on the adsorption and diffusion of nitrogen atoms on the surface of body-centered cubic iron, the new study by Professor Zhang Shihong’s team from AHUT revealed the catalytic effect of rare-earth nitriding Infiltration mechanism.

The related paper entitled "First-principles analysis on the role of rare-earth doping in affecting nitrogen adsorption and diffusion at Fe surface towards clarified catalytic diffusion mechanism in nitriding" was published by Acta Materialia, a top international journal in the field of metal materials.

Nitriding and carburizing are important methods to strengthen the surface of iron-based alloys. The addition of rare earth during nitriding or carburizing will reduce processing time, increase thickness, improve microstructures and mechanical properties of modified surface layers. There are extensive applications for RE-nitriding and RE-carburizing in experimental researches and industrial manufacture.

It is reported that rare earths are widely used in surface treatment technologies such as carburizing, nitriding, and spraying. Rare earth-assisted nitriding has been proven to help promote the diffusion rate, increase the thickness of the layer and improve the performance of the layer. While the corresponding mechanism is not yet clear.

It is understood that in this study, the body structure and surface structure properties of body-centered cubic iron were calculated, the adsorption properties of nitrogen were calculated, and the occupation of rare earth elements in body-centered cubic iron was modeled and simulated. The adsorption of nitrogen atoms on the surface of body-centered cubic iron doped with rare metal elements was calculated.

Through the bader charge and the structural changes after relaxation, a strong La-N interaction was found, which explained the increase in the adsorption energy of nitrogen atoms after La doping. The adsorption of nitrogen atoms on the subsurface of body-centered cubic iron is also calculated, and it is found that rare earth element doping is helpful to reduce the diffusion barrier. The catalytic mechanism of rare metal La and Ce was summarized.

This research of the AHUT faculty will contribute to an in-depth understanding of the role of rare earths in surface treatment technology, and provide theoretical support for the optimization of rare earth surface treatment technology, providing an example for first-principles to reveal the micro-mechanism of surface dispose of.

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