Design and fabrication of biocompatible copper based shape memory alloy by spark plasma sintering

Abstract

Copper based shape memory alloys are at the forefront of R&D for biomedical applications due to their good shape recovery, ease of fabrication, excellent thermal and electrical conductivity, antibacterial properties, and corrosion resistance. Spark plasma sintering (SPS) is a consolidated powder metallurgy process, which offers biocompatibilities to the materials by controlling grain growth, forming desired phases and controlled number of porosities. In the present study, two type of shape memory alloys- CuAlNi and NiTiCu have been fabricated by the SPS method. Studying the ternary phase diagram of the alloys, the composition has been chosen. The SPS parameters have been determined through multiple trials. CuAlNi and NiTiCu alloys have been sintered respectively at 475℃and 730℃.The present study aims to find out the effectiveness oflower sintering temperature and pressure for sintering the shape memory alloys. After selecting the material and experimental parameters, the sample powders have been prepared by wet ball milling at lower ball powder ratio (BPR) and lower milling hour. DSC analysis of the powder has been done to find out the melting point of the alloy powders and the temperatures for different phase formations. XRD, SEM and EDS analysis of the sintered CuAlNi and NiTiCu samples have been carried out to identify the phases and to see the morphology of the samples. Micro hardness of the sintered alloys has been measured and static corrosion test have been done on the sample to find out the corrosion rate. The DSC analysis of the alloy powders provides evidence that successful sintering of CuAlNi and NiTiCu is possible at lower SPS and ball milling parameters. XRD, SEM and EDS results also confirm the presence of desired phases in the sintered alloys. The Vickers hardness values of CuAlNi and NiTiCu refer to the further modification of CuAlNi sample is required whereas the hardness of NiTiCu alloys already have the desired values. The corrosion rates of presently studied CuAlNi alloys are lower. But corrosion resistance of NiTiCu samples in the present study requires further improvement.