Mechanical properties and fatigue behaviour of the Ti10Ta alloy


Catarina Valentea, Josu Leundab, Teresa Morgadoc,d, Alexandre Velhinhoe*

a FCT NOVA - DEMI Mechanical and Industrial Engineering Department, Faculty of Sciences and Technology, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica /Portugal

b IK4-TEKNIKER - Advanced Manufacturing Technologies Unit, Polo Tecnológico de Eibar, Calle Iñaki Goenaga 5, 20600 - Eibar (Gipuzkoa), Spain

c LNEC- CIC - Scientific Instrumentation Centre, Av. Do Brasil, 101, 1700-066 Lisboa/ Portugal

d IPT Polytechnic Institute of Tomar, Escola Superior de Tecnologia de Abrantes, Rua 17 de Agosto de 1808, 2200-370 Abrantes/ Portugal

e CENIMAT Materials Research Center, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica/ Portugal

Knowledge about the mechanical properties of the various types of Ti-Ta alloys is scarce, and does not cover the fatigue behaviour of the material. The documented information is insufficient, particularly for the specific case of Ti-Ta containing 10 % (wt% - weight percentage) tantalum. The scarcity of information is even more striking when the Ti10Ta alloy is produced by the LASER cladding process. The focus on these innovative alloys arises from their low Youngs Modulus, coupled with the inherent proprieties of tantalum, which are of interest e.g. for biomedical engineering applications. LASER cladding, a processing technique belonging to the group of the LASER technologies, allows the attainment of the elevated temperatures which are essential to work with high melting point elements like titanium and tantalum. The objective of the present work is to study the mechanical behaviour of the Ti10Ta alloy produced by the LASER cladding process, including its fatigue behaviour through the determination of the corresponding S-N curves. For that purpose, the mechanical characterization of the alloy was performed, comprising a set of hardness, tensile and fatigue tests. The standard specimens of the Ti10Ta alloy used were produced by the LASER cladding technology, with continuous feeding/deposition of powders assisted by a LASER heat source. Specimens were cut from the LASER clad Ti10Ta blocks by wire-EDM (wire-Electrical Discharge Machining). From these tests the Vickers hardness of the alloy was determined. Also, the tensile stress-strain curves were established, allowing the estimation of the alloys Young´s modulus, yield and tensile strength (together with the corresponding strain values), strain after fracture and the cross sectional area reduction, leading to conclude about the ductile behaviour of the alloy. Additionally, the equation for the uniform plastic flow regime of the material was established. As for the fatigue behaviour, the