Fig. 1. Microstructural features of base metal. (a) Distribution of twinning boundary; (b) morphology of particle phase; (c) mapping of all elements in the vicinity of particle phase; (d) Fe element mapping; (e) Co element mapping; (f) Ni element mapping; (g) Nb element mapping; (h) Ti element mapping

Fig. 2. Schematics of laser welding process. (a) Longitudinal plane; (b) horizontal plane

Fig. 3. Transversal weld formation on a macro scale. (a) Optical microscope mode; (b) back scattered electron mode

Fig. 4. Microstructural morphologies of weld in transversal section. (a)(b) Top site; (c)(d) middle site；(e)(f) bottom site

Fig. 5. Microstructural evolution near fusion line. (a) Top site; (b) middle site

Fig. 6. Distribution of Laves phase in weld. (a) Columnar zone; (b) central zone

Fig. 7. Epitaxial growth of grains near fusion line. (a) Band contrast map; (b) Σ3 grain boundary; (c) grain map; (d) grain boundary map

Fig. 8. Growth of columnar grains in weld. (a)(c) In the middle of weld；(d)(f) in the top of weld

Fig. 9. Crystal orientation. (a) Near fusion line; (b) columnar grains in the middle of weld; (c) columnar grains in the top of weld