Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Abstract

Zinc (Zn) is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties. In this work, laser powder bed fusion (LPBF) additive manufacturing was employed to fabricate pure Zn with a heterogenous microstructure and exceptional strength-ductility synergy. An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99% using a laser power range of 80–90 W and a scanning speed of 900 mm/s. The Zn sample printed with a power of 80 W at a speed of 900 mm/s exhibited a hierarchical heterogenous microstructure consisting of millimeter-scale molten pool boundaries, micrometer-scale bimodal grains, and nanometer-scale pre-existing dislocations, due to rapid cooling rates and significant thermal gradients formed in the molten pools. The printed sample exhibited the highest ductility of ~12.1% among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength (~128.7 MPa). Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternatively arrangement of bimodal Zn grains with pre-existing dislocations. Additionally, continuous strain hardening was facilitated through the interactions between deformation twins, grains and dislocations as strain accumulated, further contributing to the superior strength-ductility synergy. These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.

Laser-beam powder bed fusion of magnetostrictive Fe81Ga19 alloys: parameter optimization, microstructural evolution and magnetostrictive properties

“…In the present study, the motion of magnetic domains in the LPBF-prepared Fe 81 Ga 19 alloys would be hindered by grain boundaries and defects such as dislocations and pores, which probably caused by high energy impact and rapid solidification of LPBF process, during the magnetization process. However, the preferentially aligned columnar grains, which induced by the high temperature gradient of LPBF, contributed to the reduced barriers of magnetic domain motion [69,70], thus resulting in extremely low hysteresis in overall.…”

Microstructure development of Ti scaffold by laser powder bed fusion with chemical polishing and its mechanical properties, biocompatibility

“…It was the reason that the previous layer of Ti powder was fully remelted under the action of laser radiation, resulting in a relatively uniform heat transfer and forming a continuous and smooth scanning trajectory. Generally, the scan tracks were related nearly to the stability of molten pool [28]. The continuous and clear laser scanning track represented the more stable molten pool during the moulding process, thus forming the dense microstructure.…”

Reactive Oxygen Species Responsive Nitric Oxide Release for Enhanced Photodynamic Antibacterial Therapy of Scaffolds

“…Afterward, the mixed powder was obtained after centrifugation, stoving, and grinding. Finally, the scaffolds were fabricated by selective laser sintering (SLS). , The main printing process parameters were as follows: a scanning speed of 160 mm/s, a laser power of 2.7 W, and a scanning spacing of 0.04 mm . For convenience, the scaffold was defined as AuKN-LA/PLLA.…”

“…29,30 The main printing process parameters were as follows: a scanning speed of 160 mm/s, a laser power of 2.7 W, and a scanning spacing of 0.04 mm. 31 For convenience, the scaffold was defined as AuKN-LA/PLLA. Additionally, PLLA, KN/PLLA, and AuKN/PLLA scaffolds were fabricated as well.…”