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 degrees 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 mu m 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 degrees C. Moreover, an increase in preheating temperature from 100 to 400 degrees 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 mu m/year) and the highest corrosion rate (1.68 +/- 0.03 mu m/year) were observed at substrate preheating temperatures of 200 and 100 degrees C, respectively.