2016) System development, formability quality and microstructure evolution of selective laser-melted magnesium, Virtual and Physical Prototyping, 11:3, 173-181, ABSTRACT A selective laser melting (SLM) system, which consisted of a fibre laser, a three-dimensional motion platform and a motion control system, was developed in this study. The effect of process parameters on the microstructure evolution of SLMed magnesium parts was investigated. The results revealed that under an irradiation of laser energy density <3.0 J/mm, the powder remained in the discrete state. At a laser energy density 3.0-6.0 J/mm, the powder partially melted and sintered together, yielding incompact tracks. As the energy density increased to 6.0-12.0 J/mm, the powder fully melted forming continuous and smooth tracks. With a further increase in the laser energy density evaporation of the powder occurred. Dense magnesium parts free of pores and cracks were successfully fabricated with the optimal energy density of 10.0 J/mm. The immersion experiment revealed that the degradation product was mainly consisted of Mg(OH) 2 , which slowed down the degradation rate acting as a protective layer. ARTICLE HISTORY

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Medical titanium and alumina (Al2O3) bioceramic are widely utilized as biomaterials. A reliable brazed joint of titanium and alumina was successfully obtained using biocompatible Au foil for implantable devices in the present study. The interfacial microstructure and reaction products of titanium/Au/Al2O3 joints brazed under different conditions were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). In this study, the typical interfacial microstructure of the titanium/Au/Al2O3 joint was titanium/Ti3Au layer/TiAu layer/TiAu2 layer/TiAu4 layer/Au + granular TiAu4 layer/TiOx phase/Al2O3 ceramic. With increasing brazing temperature or holding time, the thicknesses of Ti3Au + TiAu + TiAu2 layers adjacent to the titanium substrate increased gradually. Shear tests indicated that the joint brazed at 1115 °C for 3 min exhibited the highest shear strength of 39.2 MPa. Typical fracture analysis displayed that the crack started at the Al2O3 ceramic and propagated along the interface of TiAu2 and TiAu4 reaction layers.