No abstract

Metal additive manufacturing (AM) is an innovative manufacturing technique that can build complex and high value metal parts layer by layer using a computerized three‐dimensional solid model. Powder bed fusion (PBF) is one of the most common AM techniques. It sequentially processes a powdered feedstock in thin layers and solidifies it by either a laser beam or an electron beam. However, PBF induces microstructural defects that can adversely affect the performance of the manufactured components. These undesirable defects including voids and porosities must be avoided or minimized to limit their negative effects on mechanical properties and to ensure the consistency and repeatability of AM parts. The present article provides an overview of the formation mechanisms of pores in AM metals and some emerging techniques for the detection and quantification of pores. The review also highlights other common defects in PBF parts such as microstructural features associated with keyhole mode of melting.

No abstract

Some of the critical properties for a successful orthopedic or dental implant material are its biocompatibility and bioactivity. Pure titanium (Ti) and zirconium (Zr) are widely accepted as biocompatible metals, due to their non-toxicity. While the bioactivity of Ti and some Ti alloys has been extensively investigated, there is still insufficient data for Zr and titanium-zirconium (TiZr) alloys. In the present study, the bioactivity, that is, the apatite forming ability on the alkali and heat treated surfaces of Ti, Zr, and TiZr alloy in simulated body fluid (SBF), was studied. In particular, the effect of the surface roughness characteristics on the bioactivity was evaluated for the first time. The results indicate that the pretreated Ti, Zr and TiZr alloy could form apatite coating on their surfaces. It should be noted that the surface roughness also critically affected the bioactivity of these pretreated metallic samples. A surface morphology with an average roughness of approximately 0.6 microm led to the fastest apatite formation on the metal surfaces. This apatite layer on the metal surface is expected to bond to the surrounding bones directly after implantation.