Tribological Behavior of NiTi Alloy Produced by Spark Plasma Sintering Method

The tribological behaviors of NiTi alloy produced by the spark plasma sintering (SPS) method before and after annealing were investigated at various loading conditions via indentation, scratch, and wear tests. Indentation tests were performed by a pyramidal Berkovich indenter, while scratch and wear tests were carried out by a diamond Rockwell spherical indenter at room temperature. The annealing of the as-prepared samples was performed at 350, 450, and 550 degrees C in the ambient atmosphere. The influence of the annealing temperature on the sample behavior towards tribological study was investigated here. The results indicated that the alloy annealed at 350 degrees C showed a higher hardness compared to the other annealed alloys. The scratch and wear resistance of the annealed sample at 350 degrees C showed a better performance in comparison to the other samples under a constant load. The high wear resistance of the annealed NiTi alloy may be attributed to its metastable R-phase. The detection and evaluation of acoustic emissions during the nano/micro-tribomechanical testing proved to be a very effective way for the exploration of the durability of SPS NiTi alloys.