Effect of substrate cooling on the epitaxial growth of Ni-based single-crystal superalloy fabricated by direct energy deposition

The columnar-to-equiaxed transition (CET) or the formation of stray grains in the laser melting deposition is the least desirable for the repair of single-crystal blades. In this work, the forced water-cooling was conducted on a single-crystal René N5 substrate during the direct energy deposition (DED). The single track remelting, one-layer, two-layer, and eight-layer depositions were investigated to explore the grain growth mechanism. The...