Effect of Cr ion implantation on surface morphology, lattice deformation, nanomechanical and fatigue behavior of TC18 alloy

Cr ions with doses of 3.56, 5.53 and 7.12 x 10(16) ions/cm(2) were implanted on the TC18 alloy by ion implantation technique. Its effects on the surface morphology, lattice deformation, residual stress, nanomechanical and fatigue behavior were studied in detail. Results showed that irradiation damage and cascade collision during Cr implanted reduced the roughness of TC18 alloy, from the 114.61 nm to the minimum 36.74 nm at 5.5 x 10(16) ions/cm(2) dose. Surface XRD test indicated the diffraction peaks of TC18 alloy at 35.298 degrees 40.261 degrees and 53.198 degrees were obvious shifted after Cr ions implantation. The shifted direction and amplitude of diffraction peak was closely related to the implantation dose. The nanohardness and elasticity modulus of TC18 alloy first increased and then decreased with the increasing of implantation dose caused by solid solution strengthening and decreasing dislocation density. The fatigue life of TC18 after Cr ion implantation was slightly improved at high stress level (> 460 MPa). When the stress level was lower than 460 MPa, it seemed that Cr ion implantation had little effect on the fatigue life of TC18 alloy.