By means of a surface plastic deformation method a nanocrystalline (NC) intermetallic compound was in situ synthesized on the surface layer of bulk zirconium (Zr). Hardened steel shots (composition: 1.0C, 1.5Cr, base Fe in wt.%) were used to conduct repetitive and multidirectional peening on the surface layer of Zr. The microstructure evolution of the surface layer was investigated by X-ray diffraction and scanning and transmission electron microscopy observations. The NC intermetallic layer of about 25 μm thick was observed and confirmed by concentration profiles of Zr, Fe and Cr, and was found to consist of the Fe 100 - xCr x compound with an average grain size of 22 nm. The NC surface layer exhibited an extremely high average hardness of 10.2 GPa. The Zr base immediately next to the compound/Zr interface has a grain size of ∼ 250 nm, and a hardness of ∼ 3.4 GPa. The Fe 100 - xCr x layer was found to securely adhere to the Zr base. ; Department of Mechanical Engineering