Characterization of Mo surface modified Ti by indentation techniques

• The Mo modified layer is duplex, containing a deposition layer and a diffusion layer.
• The Mo modified layer is continuous and compact.
• The Mo modified layer possesses higher hardness, elastic modulus and plasticity.
• The Mo modified layer could deform compatibly with the Ti substrate.

Using the plasma surface alloying technique, the Mo modified layers on Ti substrates were obtained. Being duplex, the Mo modified layer contains a Mo deposition layer and a Mo diffusion layer. Microindentation tests were performed on the surface of the Mo modified layer by two loading types, i.e. linear loading type and continuous multi-cycle loading type which can link the nano and micro range indentation values. In the microindentation process, acoustic emission testing was adopted in order to investigate cracking of the Mo modified layer. Nanoindentation tests were performed not only on the cross section of the Mo modified Ti, but on the surface of the untreated Ti plate (before alloying treatment). The experimental results indicate that the whole Mo modified layer possesses higher hardness, elastic modulus and remains relatively fine plasticity. Better than the hard film/soft substrate system, the graded Mo diffusion layer could coordinate the deformation between the Mo deposition layer and the Ti substrate.