Effect of La on microstructure and corrosion behavior of 10%TiB2(p)/Al–5%Cu composites

Abstract

The effect of La on microstructure and corrosion behavior of 10%TiB2(p)/Al–5%Cu composites was studied by using computer-aided cooling curve analysis (CA-CCA), X-ray diffraction, EDS, SEM, TEM and electrochemical testing. The experimental results showed that the La addition reduced the solidification rate of composites, decreased the nucleation temperature of primary α-Al, enhanced the transformation temperature of Al–Cu eutectic and narrowed the liquid–solid interval. Meanwhile, Al2.12La0.88 phase formation was found after adding La to the composites, and the precipitation of CuAl2 phase decreased with the increase of La content. The segregation of large agglomerates containing TiB2 clusters and second phases was improved obviously after the addition of La, which resulted in more uniform microstructure of composites. Moreover, proper La enhanced the corrosion resistance of 10%TiB2(p)/Al–5%Cu composite in 3.5% sodium chloride solution.