Influence of Aging Parameters on the Corrosion Resistance of a Biocompatible Ni50.6Ti49.4 Shape Memory Alloy

The paper show the results of electrochemical tests made in order to reveal some corrosion resistance features obtained when performing aging heat treatments at different temperatures and holding times on a shape memory Ni50.6Ti49.4 alloy. The transformation temperatures of the Ni50.6Ti49.4 alloy are already indicating it as a potentially biocompatible one and a final choice must be made after assessing its corrosion resistance as a consequence of the optimum combination choice of the aging temperature and holding time parameters. The best corrosion resistance in artificial saliva after aging heat treatment was found on the sample which was heat treated at 510 degrees C/75 min/cooled with 5 degrees C/s. The phenomena backing up this conclusion are the raising of the Ti content of the matrix induced by the dynamics of the stable and metastable precipitates formed during the aging, as well as the changes in the stress level associated to the total boundary surfaces between these phases and the matrix.