Making Combinatorial Libraries of Titanium Based Alloys by Direct Metal Deposition Technique.
- PDF / 90,736 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 85 Downloads / 134 Views
0894-LL03-23.1
Making Combinatorial Libraries of Titanium Based Alloys by Direct Metal Deposition Technique. Natalia Pimenova and Thomas L. Starr; Chemical Engineering Department, University of Louisville, Louisville, Kentucky. ABSTRACT α/β type titanium alloys, such as Ti-6Al-4V and Ti-6Al-7Nb, have been used for orthopedic implant materials because of their combination of biocompatibility, corrosion resistance and mechanical properties. However, toxicity of alloying elements is a concern. In this project, it is proposed to design the new type of titanium alloys composed of non-toxic elements, such as Ti, Al, and Fe with lower modulus of elasticity and greater corrosion resistance. To find the optimal ratio of components in the Ti-Al-Fe system is important. The composition of the alloy determines its properties. Using combinatorial approach the optimal ratio can be found relatively easily. Direct metal deposition (DMD) is a novel precise manufacturing process for fabricating metal parts directly from Computer Aided Design (CAD) solid models. The DMD process allows making several layers of different composition on one substrate. One sample includes several Ti-xAl-yFe alloys at once. This combinatorial library dramatically reduces the time and cost of the investigation. The structure, mechanical and electrochemical properties of each new composition was studied using scanning electron microscopy (SEM) with energy-dispersive X-ray fluorescence analyzer (EDAX ZAF®), and electrochemical polarization method. INTRODUCTION Direct metal deposition technique (DMD) enables fabrication of several titanium alloys in one piece. Iron and aluminum additives keep the titanium alloy in either alpha phase or alpha/beta or beta phase. During welding of the titanium alloys containing only α- phase stabilizer (Al) the β- phase transform to α- phase having weld zone hardness and tensile strength similar to that of the parent metal (Ti). By contrast, alloys with higher β- phase stabilizer content, i.e. those of the α/β type, develop a supersaturated martensite having properties which, depending on composition, can differ markedly from those of titanium. Using titanium alloys as biomedical implant material requires excellent corrosion resistance. The most common alloy in tissue engineering, Ti-6Al-4V, demonstrates similar corrosion resistance similar to titanium but has also better mechanical properties. However this alloy includes vanadium which has high toxicity. Iron is a non-toxic beta-phase stabilizer. The principal goal of this investigation is to develop a comprehensive methodology for designing and optimizing titanium alloys without vanadium (Ti-xAl-yFe) using the combinatorial method. Goals of this work are reduction of alloy design costs, exploration of larger number of alloy compositions, and identification and optimization of new Ti-Al-Fe alloys with improved properties for future implantation in human body. Demonstration of these objectives affirms the reliability of the methods used in this investigation and allows it to be
Data Loading...
