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 Ti2Co 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.
Highlights
Nowadays Ti based alloys and Co based alloys are the materials more commonly used to fabricate biomedical implants 1-4
The instantaneous volume depends on the densification during sintering and it can be estimated from the dilatometry data, in where, the radial displacement is assumed to follow the same variation as the measured axial one, with a corrective factor being the final axial to radial shrinkage ratio
The relative density is defined as the weight density of the compact divided by the theoretical density of the fully dense Ti6Al4V/CoCrMo composite at room temperature, which was calculated by using the mixture law: tt = t1 f1 + t2 f2 [4]
Summary
Nowadays Ti based alloys and Co based alloys are the materials more commonly used to fabricate biomedical implants 1-4. In order to reduce the stress shielding and to improve the citocompability, materials with large pores were developed by using different fabrication techniques 7-9 where space holder 10-12 and additive manufacturing 13-15 are the most promising. The wear properties of the Ti6Al4V alloy are relatively low, several works were dedicated to improve the surface properties. In order to overcome this disadvantage, coatings of harder materials were realized . Other works, dealing with improving wear properties, developed composites materials based on the Ti6Al4V alloy with ceramic reinforcing particles, which presented good results, improving up to 2 times the hardness of the Ti6Al4V alloy . Other works, dealing with improving wear properties, developed composites materials based on the Ti6Al4V alloy with ceramic reinforcing particles, which presented good results, improving up to 2 times the hardness of the Ti6Al4V alloy . 19-22
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