The rapid solidification characteristics of Ni-based alloy fabricated by laser engineered net shaping

Laser engineered net shaping (LENS) has been used to build up solid samples from the powders of nickelbronze. The characteristics of the as-fabricated samples such as layer growth profile, grain growth morphology, remelting condition, defects, etc., have been analyzed in detail. It has been found that the layer profile determined by the laser power and powder feeding rate. Long and fine columnar grains dominate in the microstructure. The thickness of remelted zone affected the manufacturing efficiency and in order to keep metallurgical bonding between layers a certain remelted thickness is necessary. Pores appeared in the structure when the input power was insufficient and the small voids are maybe inevitable because of the rapid solidification course. Shape curling can be efficiently eliminated by pre-heating substrate. These structural characteristics can be concluded to the untraditional rapid solidification of LENS processing.