INFLUENCE OF GRAIN SIZE ON MICROSTRUCTURE AND POROSITY OF BIOCOMPTIBLE TI-35,5Nb-5,7Ta ALLOY PROCESSED VIA POWDER METALLURGY

Beta-titanium alloys containing only fully biocompatible elements are very perspective materials for production of bioimplants. They have good properties for use as biomaterials, including above mentioned biochemical compatibility, low elastic modulus (important for biomechanical compatibility), in comparisson with previously used alloys. Moreover they are suitable for forging. Perspective method with respect to final price is powder metallurgy. There are several advantages in compare with usual methods like arc melting. On the other hand the problem of powder metallurgy could be the porosity of the final product after sintering. In this paper, the influence of the grain size and parameters of sintering used during the preparation of biocompatible Ti-35,5Nb-5,7Ta alloy on its microstructure and compactness, which influence properties of the alloy, were studied. Measurements of porosity depending on sintering time at 1400°C were made. Furthermore the microstructure of specimens and local chemical composition were observed. The object was to obtain fully compact specimen without pores by hot forging of specimens prepared via CIP method (cold isostatic pressing and subsequent sintering).