This master's thesis investigated the effect of diffusion bonding temperature on the development of microstructure and diffusion processes in the titanium–gold system. The aim of the research was to determine the influence of processing parameters on the formation of the diffusion zone, the development of intermetallic compounds, and the diffusion behaviour between the two materials. Particular attention was focused on microstructural changes occurring at different diffusion bonding temperatures.
For the experimental work, specimens were prepared using commercially pure titanium and 24-carat gold. Diffusion bonding was performed using a Gleeble thermomechanical simulator at temperatures of 900 °C, 950 °C, 1000 °C, and 1050 °C, while a specimen processed at 400 °C was used for comparison with low- temperature diffusion conditions. Following thermomechanical treatment, the specimens were metallographically prepared and examined by optical microscopy and scanning electron microscopy. The chemical composition of individual phases was determined using Energy-Dispersive X-ray Spectroscopy (EDS). In addition to the experimental investigation, diffusion simulations were carried out using a diffusion modelling software module DICTRA. DICTRA is a module of the Thermo-Calc software used to simulate diffusion-controlled processes and predict microstructural evolution in multicomponent alloys using the CALPHAD method.
The results showed that increasing temperature enhanced the extent of diffusion between titanium and gold, increased the width of the diffusion zone, and promoted the formation of intermetallic compounds. The phases Ti3Au, TiAu, TiAu2, and TiAu4 were identified within the diffusion zone. The development of a lamellar microstructure in the titanium region was also observed, becoming more pronounced with increasing temperature. Experimentally determined diffusion distances of gold atoms were approximately 19 μm at 900 °C and 950 °C, 21 μm at 1000 °C, and 38 μm at 1050 °C.
It was concluded that temperature is the key parameter governing diffusion bonding in the titanium–gold system. The results demonstrated that the formation of intermetallic phases and the resulting microstructure can be controlled through appropriate selection of processing parameters.
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