Direct Laser Deposition of a Single-Crystal Ni3Al-Based IC221W Alloy

Single-crystal (SX) nickel aluminide alloys have potential for structural applications where high-temperature strength and oxidation resistance are required. In this work, SX deposits of the Ni3Al-based IC221W alloy were produced on a SX Ni-base superalloy substrate by means of the laser-engineered net shaping (LENS) process. The microstructure of the deposits was characterized. The effects of processing parameters on the SX solidification in the melt pool and on the fabricabil-ity by LENS were investigated. A simple relationship between the ratio of the temperature gradient to the growth velocity and the processing parameters was derived, which can be used qualitatively to guide the proper selection of processing conditions to maintain the columnar dendritic growth during the laser deposition. On the basis of analyses and experiments, the effects of processing param-eters on the susceptibility to stray grain formation and solidification cracking are discussed. I