Microstructures of Electron Beam Melted (EBM) Biomaterial Ti-6Al-4V
- PDF / 3,830,078 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 30 Downloads / 251 Views
1132-Z09-06
Microstructures of Electron Beam Melted (EBM) Biomaterial Ti-6Al-4V Adnan Safdar1, Liu-Ying Wei1 Division of Materials Science, Malmö University, SE-205 06 Malmö, Sweden. ABSTRACT: Ti-6Al-4V alloy is an attractive biomaterial. The current work evaluates the microstructures of the solid and net-shape Ti-6Al-4V alloy produced by Electron Beam Melting (EBM) system using SEM/EDX and optical microscope. The microstructures are influenced by the cooling rate, processing parameters of the EBM system and re-heating of the existing layer during the melting of subsequent layers. Layer structure and columnar grains have been observed, with growing direction parallel to the built direction. The interior of these grains consists of alternating α / β phases. The β phase in the colonies resembles rod shape embedded in the α platelet. Along the grain boundaries more or less continuous α layers were observed. In comparison to solid samples uneven surfaces and pores were seen in the net shape structure. Microhardness evaluation of the EBM produced alloys was also carried out and compared with conventionally produced alloys. INTRODUCTION: Pure titanium and it’s alloys, especially Ti-6Al-4V, are one of the most attractive and widely used materials in aerospace industries. These are also considered an excellent biomaterial owing to their superior biocompatibility, high corrosion resistance and better mechanical properties in comparison to conventional biomaterials [1]. Electron Beam Melting (EBM) is one of the Free Form Fabrication (FFF) technique used for the medical implant fabrication [2-3]. EBM system uses the additive approach to built 3D solid as well as near net shaped structures by melting the metallic powder in vacuum chamber. The EBM system is fully computer controlled. It consists of an electron beam generating system (Electron Gun), a build chamber and a computer system to control the whole process. The machine spreads the thin layers of metallic powder in build chamber and electron beam melts the layer to achieve required 3D geometry according to a predefined 3D Computer Added Design (CAD) file. During the whole built, the electron gun and build table remain stationary while the electron beam scans the build table with the help of scanning coils. This scanning results in melting and subsequent solidification of the metallic powder’s layer. This system allows the fabrication of one complex geometrical unit instead of the multiple pieces that are required to be assembled later. The EBM systems are almost 90% power efficient and the vacuum in the build chamber provides oxygen free environment [4]. The vacuum environment also aids to achieve precise geometry. This technology has the ability to build dense parts similar to any wrought material. A beam of high energy electrons is produced in the electron gun when 60 KV voltage is applied to a tungsten filament. This beam is focussed by the combination of electrostatic / electro-magnetic lenses on to the build table with power density of up to 100 Kw/cm2 [5]. The beam
Data Loading...
