Investigation on the influence of precipitated phase on corrosion resistance of the Ni-based alloys

摘要

The influence of precipitated phases in Ni-based alloys during solid solution aging treatment on the performance of Ni-based alloys was investigated by means of metallographic observation,scanning electron microscope (SEM),and transmission electron microscope (TEM).The variation of microstructure and resultant phases as a result of solid solution aging treatment at different temperatures was discussed.The results show that the heat treatment temperature has significant influences on the type as well as quantity of precipitation phases.Lots of phases precipitated at grain boundaries,the distribution of precipitated phases are characterized by mesh-like structure.The corrosion tests results indicate that there is a potential difference between grains and grain boundaries due to the precipitation of chrome carbide at grain boundaries,resulting in pitting corrosion occurred preferentially at grain boundaries,consequently,the corrosion resistance of Ni-based alloys is reduced.In order to enhance the corrosion resistance of Ni-based alloys,it is expected to control the carbon content in a lower range and proper heat treatment process to avoid large amount precipitation of chrome carbide.