Influence of Island Scanning Strategy on Microstructures and Mechanical Properties of Direct Laser-Deposited Ti–6Al–4V Structures

To investigate the influence of island scanning on the microstructures and mechanical properties of direct laser-deposited Ti–6 Al–4 V structures,two samples are prepared using island scanning and orthogonal successive scanning,respectively.The microstructures,relative density,and mechanical properties of the samples prepared using these two scanning strategies are compared.Each sample exhibits columnarβ-grain morphology and basket-weave microstructure characterization.The grains of the sample prepared using island scanning are significantly finer than that prepared by orthogonal successive scanning due to faster cooling during deposition.However,the relative density of the sample prepared using island scanning was slightly smaller due to the concentration of lack-of-fusion pores at the overlap zone of the island.Tensile testing at room temperature indicates that the ultimate tensile strength and yield strength of the sample prepared using island scanning is enhanced due to finer grains,while the ductility of the sample is weakened due to defects.

Forming quality,mechanical properties,and anti-inflammatory activity of additive manufactured Zn–Nd alloy

Zinc(Zn)has recently been recognized as a promising bone repair material due to its inherent biodegradability and favorable biocompatibility.In this work,rare earth neodymium(Nd)was introduced into a Zn-based alloy fabricated using a laser powder bed fusion(LPBF)process.Results showed that addition of Nd significantly improved the melt fluidity and reduced the evaporation of Zn,thereby achieving parts with a high densification rate of 98.71%.Significantly,the Nd alloying treatment effectively refined the grain size from 25.3 to 6.2μm.Nd Zn5 eutectics precipitated and contributed to a second-phase strengthening effect.As a result,the tensile strength increased to(119.3±5.1)MPa and the Vickers hardness to(76.2±4.1).Moreover,the Zn–Nd alloy exhibited good anti-inflammatory activity,as the Nd ions released during degradation had a strong affinity with cell membrane phospholipids and consequently inhibited the release of inflammatory cytokines.It also presented favorable cytocompatibility,showing great potential as a bone repair material.