Hot corrosion resistance of a Ti–Mo–Nb–Al–Si titanium matrix composites reinforced with in-situ TiC prepared by powder metallurgy

Abstract

A mixture of the Ti–Mo–Nb–Al–Si matrix powder and Carbon nanotubes (CNTs) particles were used as the raw powder to produce the in situ TiC reinforced titanium matrix composites (TMCs) via powder metallurgy. The effects of various contents of CNTs on the microstructure, phase composition and hot corrosion behavior of the composites were investigated. The results show that the corrosion mass gain of the composites with CNTs content of 1.0 wt% was the minimum (18.73 mg·cm−2), which was about 44.4% lighter than that of the matrix (33.70 mg·cm−2). XRD results show that the corrosion phases were mainly composed of TiO2, Al2O3, SiO2, Ti(SO4)2, NaTiO2 and TiS. According to the SEM results, the grain size of the as-sintered composites can be refined by adding CNTs. With the increase of CNTs content, the grain size became smaller and smaller. The cross-sectional morphology shows that the oxide layer of the composites with 1.0 wt% CNTs after corrosion was denser and thinner (21.44 μm). It was about 82.13% thinner than the oxide layer of the matrix (120.00 μm). All the results show that the TMCs with 1.0 wt% CNTs have better hot corrosion resistance.