Formation of Nickel Aluminide In Situ via Dual-Wire Arc Cladding

This study explores the impact of substrate preheating temperature on the in situ formation of nickel aluminide intermetallic compounds using the dual-wire gas tungsten arc welding process. The findings reveal that as the preheating temperature rises from 100 to 400 °C, the dilution increases from 28.4 to 31.8%. Concurrently, the size of dendrites (primary dendrite arm spacing) increases from 4.5 ± 0.8 to 8.9 ± 0.5 µm with the elevation of substrate preheating temperature. Needle-shaped NiAl phases emerge within the microstructure at the dendritic structure interface as the preheating temperature decreases from 400 to 100 °C. Moreover, an increase in preheating temperature from 100 to 400 °C leads to a decrease in average hardness and ultimate tensile strength from 487.4 ± 52.1 to 395.3 ± 33.2 HV and 776.3 ± 10.3 to 745.5 ± 11.6 MPa, respectively. The lowest corrosion rate (0.59 ± 0.04 µm/year) and the highest corrosion rate (1.68 ± 0.03 µm/year) were observed at substrate preheating temperatures of 200 and 100 °C, respectively.