Semi-solid Sintering of Ti6Al4V/CoCrMo Composites for Biomedical Applications

Abstract

A composite of Ti6Al4V reinforced with CoCrMo particles is fabricated by conventional powder metallurgy and semi-solid sintering. Composites are fabricated by mixing 20% wt. of CoCrMo reinforcing particles into the Ti6Al4V matrix. Sintering is studied by dilatometry tests between 1050 and 1130 °C and compact characterization is performed by SEM and XRD. Microhardness is evaluated on the polished surface in order to obtain the mechanical properties. It is found that densification is achieved by the formation of a liquid phase due to a eutectic point formed by the Ti and Co at around 1130 °C. Composites with 93% of relative density are obtained. Their microstructure is composed by the Ti6Al4V matrix surrounded by a Ti 2 Co phase. Average microhardness of composites is higher than that obtained for monolithic samples of both alloys. It is assessed that the control of the liquid phase is the key to obtain highly dense composites that could be used as dental or orthopedic implants.

Powder Metallurgy Fabrication and Characterization of Ti6Al4V/xCu Alloys for Biomedical Applications

“…It can also be deduced that a strong solid-state diffusion of Cu to form intermetallics is achieved during the densification process. This is contrary to the observation of different systems that were sintered in a semi-solid state, in which the distribution of liquid is around the Ti64 particles either by means of a eutectic reaction [30] or the melting of one element [6]. Thus, the densification mechanism based on shrinkage during sintering and the microstructure obtained after sintering could be pore filling by eutectic liquid and growth of lamellae of Ti 2 Cu during solidification of that liquid, which is increased by solid diffusion of Cu into the Ti64 matrix.…”