ABSTRACT 
Titanium is widely used in biomedicine given its properties that include high biocompatibility, corrosion resistance and specific strength. However, its stiffness is too high in comparison to the human cortical bone where it causes difficulties with bone weakening. Although titanium is considered to be a bioinert material, it must have a superficial roughness with porosity and pore size so as to allow osseous development in order to reduce patient recovery time. In addition, its high reactivity makes manufacturing difficult since reaction with interstitial elements has a very negative effect on its properties.
In this study, porous specimens of the alloy Ti6Al4V were developed with a similar stiffness to that of the human cortical bone, and with enough strength to allow their use as an implant. To develop these pieces, two different powder metallurgy technologies have been used: the sintering of titanium beads and the space holder method.
A prior study of reactivity revealed a maximum interaction when sintering on stoneware ceramic and aluminium oxide, and a minimum reaction on yttria, which resulted in the best mechanical properties and less fragility.
Porous specimens developed by the sintering of Ti6Al4V beads have an open and interconnected porosity with a pore size proportional to the size of the microsphere beads. Their stiffness is less than 40% of the solid material, while their mechanical properties increase with temperature and time and change inversely with the size of the microspheres, which was the most influential parameter.
By contrast, specimens obtained by the space holder method present closed and isolated porosity. Its stiffness ranges from 20 to 65% of that of the solid material and, as other mechanical properties, it depends mainly on the content of spacer particles. However, removing the spacer particles immediately after compaction is of great importance to minimize the risk of reactivity caused by the prolonged contact with it.
A study of corrosion resistance was performed on the specimens developed by the space holder method. This study revealed that it was difficult to accurately determine the rate of corrosion. However, no significant differences were observed between the developed pieces and a forged piece.
Similarly, improving the fatigue resistance and mechanical properties of porous pieces by heat treatment is very complex. While a refinement of the microstructure without incurring reactivity was observed in treatments applied in the laboratory, the structure could not be refined in conventional ovens without increasing fragility.