Influence of alloying elements on the mechanical properties of a cobalt-based alloy produced with powder metallurgy

Abstract

This work was focused on studying the effect of alloying elements on the mechanical and tribological properties of cobalt alloys. The Co-Cr-Mo alloy has been successfully used for the production of orthopaedic implants thanks to a better wear resistance than that of titanium implants. However, with the development of scientific and technological processes, there is still an ongoing effort to further improve the wear resistance and other properties of cobalt-based alloys. The aim of this research was to find a suitable alloying element, which would increase the wear resistance, while the other characteristics remain unimpaired. When choosing such an element, we have to keep in mind that it has to be non-toxic for the human body. The standard Co-Cr-Mo alloy and Co-Cr-Mo alloy with various alloying elements, specifically Nb, Si, Ti in an amount of 5 % mass fraction, were prepared using mechanical alloying followed by the compacting method called spark-plasma sintering. The influences of the alloying elements on the microstructure as well as mechanical and tribological properties were observed. Based on the obtained results, the Co-Cr-Mo-Nb alloy seems to be most suitable because the addition of niobium greatly improved the wear resistance. However, it is necessary to perform many other tests, especially the tests of corrosion resistance and biocompatibility.