Selection of Titanium Alloys for Design

Effect of the Heat-Treated Ti6Al4V Alloy on the Fibroblastic Cell Response

“…Figure 1 shows the microstructure of Ti6Al4V as received, as well as of Ti6Al4V 800 and Ti6Al4V 1050 obtained after the heat treatments. In the as received condition ( Figure 1 a), beta-phase equiaxed grains (dark zones) dispersed in the alpha-phase matrix (light zones) can be observed; meanwhile, in Ti6Al4V 800 ( Figure 1 b), the alpha-phase acted as a barrier, thickening and preventing the grain size of the beta-phase (between 1 and 5 μm) from increasing rapidly [ 8 , 9 , 10 ]. On the other hand, in Ti6Al4V 1050 alloy ( Figure 1 c) a Widmanstätten or lamellar-like microstructure can be seen, where both alpha- (light zones) and beta-phases (dark zones) form 1–2 μm thick and 40–80 μm long sheets, which are interspersed over the entire surface [ 32 , 33 ].…”

“…In order to reveal the microstructure, a standard metallographic technique was used, consisting of its grinding with SiC paper sheet, polishing to a mirror finish and etching with Kroll reagent (HF + HNO 3 and deionized water, 1:3:96) [ 9 ]. The microstructure was observed with a Nikon EPIPHOT 300 optical microscope coupled to a Nikon FDX-35 camera (Nikon Instruments Europe B.V., Amsterdam, The Netherlands).…”

“…Titanium has closer mechanical properties to the bone tissue than other metallic biomaterials, such as 316 L stainless steel and Co-Cr alloys; besides, its allotropic transformation from the alpha to beta phase, when its temperature exceeds the T TRANSUS (882 °C), is outstanding [ 8 , 9 ]. This transformation provides microstructural changes with a better mechanical performance compared to other metals.…”

“…However, Ti-beta alloys, despite being biocompatible, show high density and low resistance to wear and fatigue, whereas the alpha-beta Ti alloys mainly constituted by 6% of alpha and 4% of beta stabilizer, have their main disadvantage in the toxicity of some alloying elements, such as V. In order to inhibit and/or decrease the effect of these elements, heat treatments had been suggested, leaving them farther away from the surface so as not to be in contact with organs and/or tissues; however, few studies have addressed the issue of how microstructural changes in these alloys immersed in biological environments may affect the cell adhesion, proliferation, morphology and osseointegration [ 19 , 20 ]. Specifically, Ti6Al4V can be subjected to heat treatments below and above its transformation temperature ( T TRANSUS = 980 ± 20 °C) [ 8 , 9 , 21 ], and depending on the cooling rate it may provide different microstructures, such as globular, martensitic, bimodal and lamellar types. These microstructures can lead to modifications in the growth of passive oxide, its topography, chemical composition [ 22 ] and physicochemical surface changes, which could modify its electrochemical behavior at material/tissue interface [ 23 , 24 ], as well as cell morphology, adhesion, proliferation and differentiation [ 25 ].…”

Pilot Feedback Electronic Imaging at Elevated Temperatures and its Potential for In-Process Electron Beam Melting Monitoring

“…It is proposed that electronic imaging trials should be carried out at a range of temperatures increasing in value towards the actual in-process monitoring temperature of a demonstrator material. Ti-6Al-4V alloy was chosen to be the demonstrator material for this study due to its popularity in the field of AM, aerospace and medical industries [24,25].…”