Metallurgy of a Ti-Au alloy synthesized by controlled electric resistance fusion

In this study, the first attempt was made to synthesize a Ti-Au alloy by fusing two titanium plates and a thin gold foil between them using the small-scale resistance spot welding procedure. The main goal was to study the possibility of controlling the alloy synthesis process by predefined thermal cycles (metal heating and its cooling rate). The Ti-Au alloy microstructure, chemical and phase compositions, as well as hardness distributions were studied by scanning and transmission electron microscopy, energy dispersive X-ray analysis, and nano-indentation. As a result, a weld nugget with optimal sizes for titanium alloys was formed. The average gold content in the synthesized Ti-Au alloy was about 16 at. % (42 wt %). It was distributed rather evenly throughout the nugget volume in ratios of 10-20 at. % (30-50 wt In addition to alpha-Ti and Au particles, the alloy included the Ti3Au and TiAu2 compounds corresponding to the gold content of 25 and 67 at. %, respectively. These compounds had formed in micmvolumes contained high gold concentrations for a period of less than 3 ms. Hardness values were from 6 up to 7 GPa in the regions most enriched in gold, and they were about 4 GPa where the gold content was minimal. Based on the obtained results, some ways were proposed for the possible optimization of this research method.