Microstructure, mechanical properties and corrosion behavior of Zr-2.5Nb alloy prepared by laser powder bed fusion

This study devoted to optimize the laser powder bed fusion (LPBF) parameters for the preparation of Zr-2.5Nb alloys, and was focused on power of incident laser beam and its scanning speed. The microstructure, mechanical and corrosion properties of samples prepared at different laser powers were investigated. The results show that high quality samples were obtained with the relative densityover 99%, ultimate tensile strength of 980 MPa, and the elongation at fracture of 14.18%. At a scanning speed of 1400 mm/s, with increasing laser power from 120 to 180 W, two transformation processes: α’ martensite coarsening and transition from an acicular into a zigzag structure ( β → α’ / α → α + β ) occurred. Densification and α’ martensite transition improved ductility and corrosion resistance at optimal value of the laser power while lower or higher laser power resulted in decreasing the ductility and corrosion resistance because of unfused particles and pores. Increasing β -Zr amount and size decreased the tensile strength due to the dislocation movement. Passive films, which were spontaneously formed at different laser powers, possessed an optimum corrosion resistance at the laser power of 160 W.