Modification mechanism of Cu–Al alloy with pre-cladded Al/AlY layers treated by plasma nitriding: Experiments and first-principles calculations

Le résumé fourni par la source

The improvement in the properties of aluminum bronze alloys after nitriding is limited due to the immiscibility of nitrogen atoms with the copper matrix. To address this issue, a Cu-Al intermetallic compound prelayer is used, and the rare earth element Y is introduced to facilitate the diffusion of nitrogen atoms, thereby significantly enhancing the surface properties. The aluminum bronze alloy samples pre-cladded Al/AlY layers were obtained by low-temperature plasma nitriding, and the microstructure and properties of the composite modified layers were investigated. The results showed that a composite modified layer containing rich AlN→rich Cu 9 Al 4 →rich Al 6 Cu 6 Y was formed on the surface of Cu-Al alloy. The layer was closely bonded to the substrate and had no obvious defects. Compared to pre-cladded with Al, the thickness of the modified layer increased. By comparing with the modified layer, the pre-cladded AlY and nitrided sample exhibited the best comprehensive properties. This mainly depended on the concentration and distribution of N element in the modified layer. The results of first principles calculation confirmed that the addition of rare earth element Y could significantly reduce the solubility energy of N atom and greatly promote the nitriding process. Therefore, the concentration of nitride in the composite modified layer was increased, the grain was refined, and the final comprehensive performance was improved.

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