Characterization and corrosion behavior of NiTi-Ti2Ni-Ni3Ti multiphase intermetallics produced by vacuum sintering

An in-situ synthesis method was employed to produce NiTi-Ti2Ni-Ni3Ti multiphase intermetallics. In this regard, the amorphous/nanocrystalline Ni-Ti powders were sintered at 1300 degrees C for 2 hrs to obtain Ni-Ti alloys with dense structure. Tafel polarization tests were employed to study corrosion behavior of multiphase materials in 3.5% NaCl and 0.1 M H2SO4 corrosive media. The results indicated that the microstructure of sintered samples consists of NiTi(Fe) and Ti2Ni/Ti4Ni2Ox phases embedded in a Ni3Ti matrix. The synthesized multiphase materials had microhardness up to 873 HV1 kg.Further investigations showed the corrosion performance of multiphase samples in 3.5% NaCl solution was inferior to that of wrought NiTi alloy. In contrast, the corrosion resistance of multiphase samples in 0.1 M H2SO4 solution was comparable to that of wrought NiTi alloy. (C) 2011 Elsevier Ltd. All rights reserved.