Nanoindentation behavior of molybdenum surface-modified titanium

By using double glow plasma surface metallurgy technique, the molybdenum (Mo) surface-modified layer on titanium (Ti) was obtained. The corresponding cross-section morphology, phase formation, and element concentration were investigated by optical microscopy, X-ray diffraction (XRD), and glow discharge optical emission spectroscopy (GDOES), respectively. The experimental results indicate that the Mo modified layer is composed of a 1.7 μm pure Mo deposition layer and a 14.3 μm Mo diffusion layer. Along the sample thickness direction, nanoindentation tests were performed on the cross-section of the Mo diffusion layer and the Ti substrate (for the comparison purpose) by Hysitron TI900 TriboIndenter. The 2D and 3D residual indentation profiles of the Mo diffusion layer were obtained by scanning probe microscopy (SPM). The elastic modulus and hardness values of every indent were acquired and analyzed. According to the load-displacement curves, the plastic deformation degrees of the Mo diffusion layer and the Ti substrate were analyzed. It is indicated that the Mo diffusion layer possesses high strength-toughness.