Effect of Laser Power on Anisotropic Microstructure and Mechanical Behavior of Biomedical Ti-35Nb-15Zr (at%) Alloy Fabricated by Laser Powder Bed Fusion

다국어 초록 (Multilingual Abstract)

In this study, the anisotropy of Ti-35Nb-15Zr (at%) fabricated in situ using laser powder bed fusion (LPBF) was investigated for the first time. The effects of varying laser powers on the anisotropic microstructure and mechanical properties were investigated. The equiaxed grains growing in the horizontal section were finer than the β-columnar grains growing in the vertical section, and the grain size increased from 8.8 to 10.47 μm as the laser power increased. The difference in microstructure generally resulted in higher nanohardness in the horizontal Sect. (7.12, 6.70, and 6.49 GPa at 250, 275, and 300 W laser power, respectively) than in the vertical Sect. (5.41, 5.56, and 5.38 GPa at 250, 275, and 300 W laser power, respectively). The yield strength (1223.48 ± 27.67 MPa) and ductility (6.77 ± 0.48%) of the samples were both higher in the horizontal direction. The Young’s modulus of the samples in the horizontal direction, which reached as low as 72.82 ± 0.77 GPa, were lower than those in the vertical section, with a minimum of 77.59 ± 1.89 GPa. With increasing laser power, the yield strength in the horizontal direction, Young’s modulus, and yield strength in the vertical direction increased, whereas the yield strength in the vertical direction decreased. In particular, the Ti-35Nb-15Zr alloy exhibited better cellular activity than cast Ti6Al4V. All samples formed dense, bone-like apatite layers on the surface in different directions, demonstrating the great potential of the LPBF Ti-35Nb-15Zr alloy as an implant.