MECHANICAL PROPERTIES AND HIGH TEMPERATURE OXIDATION BEHAVIOR OF Ti-Al COATING REINFORCED BY NITRIDES ON Ti-6Al-4V ALLOY

摘要

Ti-Al alloyed coating reinforced by nitrides was fabricated by laser surface alloying technique to improve mechanical properties and high temperature oxidation resistance of Ti-6Al-4V titanium alloy. Microstructures, mechanical properties and high temperature oxidation behavior of the alloyed coating were analyzed. The results show that the alloyed coating consisted of Ti3Al, TiAl2, TiN and Ti2AlN phases. Nitrides with different morphologies were dispersed in the alloyed coating. The maximum microhardness of the alloyed coating was 906 HV. The friction coefficients of the alloyed coating at room temperature and high temperature were both one-fourth of the substrate. Mass gain of the alloyed coating oxidized at 800 degrees C for 1000 h in static air was 5.16 x 10(-3) mg/mm(2), which was 1/35th of the substrate. No obvious spallation was observed for the alloyed coating after oxidation. The alloyed coating exhibited excellent mechanical properties and long-term high temperature oxidation resistance, which improved surface properties of Ti-6Al-4V titanium alloy significantly.