Effect of Mo Ion Implantation on Stability of Nanocrystalline Copper Surface Layers

Abstract

The surface of pure copper was modified using the surface mechanical attrition treatment (SMAT) method, and molybdenum ions were implanted in the nanosurface using a metal vapor vacuum arc (MEVVA). The results of the SMAT were observed by optical microscopy (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). An obvious nanocrystalline layer and a deformation region exist on the surface. The size of the nanocrystalline layer was characterized using atomic force microscopy (AFM). The results indicate remarkable suppression on grain size, the nanocrystalline layer grows to 163nm after annealing and reduces to only 72nm due to the Mo ion implantation. In addition, the hardness of the topmost surface of the material is 3.5 times that of the SMATed copper, which is about 7 times of the value of the matrix. The above improvements most likely result from the dispersion of the Mo ions and the reactions of the crystal defects due to the SMAT and ion implantation.

Keywords

• surface mechanical attrition treatment
• ion implantation
• nanocrystalline surface layer
• microstructure
• hardness