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The dissolution of Ti–N solids in liquid titanium was investigated using experimental and numerical methods. To characterize the dissolution rate and the transport phenomena associated with the dissolution process, cylindrical Ti–N rods were immersed into a molten pool of commercially pure titanium produced using an electron beam button furnace. Tests were conducted for various immersion times to observe the evolution in the rod tip profile and measure the volume loss. Generally, the volume fraction of dissolved solid increases with increasing immersion time. A numerical model has been developed to describe the experimental process and aid in understanding the dissolution process. Overall, the predicted volume loss for different immersion times agrees well with the experimental measurements. An effective mass transfer coefficient, in the range of 4.2 × 10−5 to 4.9 × 10−5 m/s, has been derived based on the model results for the experimental conditions examined (e.g. interface velocities and temperatures in the range of 0.09 – 0.11 m/s, and 1766 – 1778 °C, respectively).

Nitrogen introduction to solid commercially pure titanium has been carried out at 1650 °C in an electric induction furnace using two different methods. An effective way to avoid the formation of the hard and brittle nitride layer (TiN and Ti2N) is reported. Microstructure and microhardness were examined on the cross-section of the nitrided samples. Multiple phase layers can be observed, and the phases in each layer were identified using X-ray Diffraction. The effects of the experimental conditions such as temperature and nitriding time on the kinetics of nitrogen diffusion were investigated. The nitrogen content within the samples was increased with increasing temperature and nitriding time. Correlations between microhardness and the nitrogen concentration have been developed for the phase(s) present in the core and the outer layers. The diffusion of nitrogen in solid titanium was simulated numerically, and the predicted nitrogen concentration profile in the rods and displacement of Ti–N phase interfaces show good agreement with the experimental observations. Energy-dispersive X-ray spectroscopy and the numerical simulation results suggest that β phase boundary composition is 2.8 wt. % N, the α phase exists within the compositional range of 5.5–6.5 wt. % and the Ti–N phase within the compositional range 7.0–15.0 wt. %, which differs from data extracted from a published phase diagram.