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Although titanium is considered to be the most successful metal for uncemented endosseous implants, its biocompatibility may be unsatisfactory in certain clinical cases. As an early osseointegration is essential in order to reduce the implant failure risk, the bioactive fixation becomes the appropriate solution for bone applications. The method requires bioactive materials such as hydroxyapatite (HA) to facilitate the chemical bonding to tissue. The present work refers to Ti-HA composites designed for endosseous implants and obtained through the classic PM route. Grade 1 c.p. Ti powder obtained through the hydriding – milling – dehydriding process, 63 - 100 μm grain size, was used. Sol-gel HA powder, grain size of less than 100 μm, was obtained through the sol-gel method. Blends of Ti and 5 to 50% HA were compacted in a rigid die (0.5 cm2), without the use of any lubricant, with 400, 500 and 600 MPa, then vacuum sintered (10-6 torr) at 1160°C for 60 minutes. Samples are well sintered with a compactness that increases with the applied compaction pressure. A transition layer can be seen in the EDX at the interface between the Ti matrix and the HA particles and is expected to increase the overall mechanical stability of compacts. The pores, essential for osseointegration, are interconnected, with irregular shapes and sizes that reach 100 μm, the critical size needed for the formation of a vital new bone. The HA content has to be limited to 30%, not to lead to an excessive brittleness. The biologic viability of compacts was assessed by immersion for 7 days into a simulated body fluid (SBF). The subsequent XRD analyses have proven that a new HA layer is formed on the surface of samples. This layer is essential for accelerating the cellular response of osteoblasts in the body.

NiTi alloys, due to the special properties they posses, good corrosion resistance, biocompatibility, and shape memory, are used successfully in the medical field. The paper presents research concerning the elaboration of the NiTi alloy in the form of spherical shape powder with hollow particles. This type of powder would be the raw material for fabricating light weight products like prosthesis or surgical implants. The aim of the research was to elaborate this type of powder and determine the alloy’s phases in correlation with the need of obtaining a specific particle shape. Along with these aspects it was attempted to form different testing samples through sintering operations.

Shape memory Titanium-Nickel alloys, also known as Nitinol, are amongst the most utilized materials with special properties in the medical field. Together with the properties of shape memory and superelasticity, these alloys have a very good biocompatibility. In this study, the equiatomic Ti-Ni alloy was obtained in the form of alloyed powder, starting from elemental high purity powders, through mechanical alloying. Specimens for testing the mechanical characteristics of the material, as well as smaller samples for biocompatibility tests were manufactured. The latter ones were prepared for implantation on live tissue, on Wistar rats and Guinea pigs. The structure of samples was studied by microscopy and X-Ray diffraction analysis. All the results have demonstrated the presence of the TiNi intermetallic compound as the quantitative dominant phase. After applying an adequate thermo-mechanical treatment, the tested samples displayed measurable shape memory effect and superelasticity. The in vivo biocompatibility tests, done according to international standards, demonstrated the material’s bio-inertness in relation with living tissue. The obtained results have shown the possibility to elaborate Ti-Ni biocompatible alloys by mechanical milling and sintering.