Effects of Dy on the Microstructure and Hardness of NiAl Alloys
Intermetallic compound NiAl is considered as a potential candidate material for bond coat in thermal barrier coating (TBC) system due to its capability of forming a continuous and uniform alumina scale at temperatures even high than 1200 ℃,but its cyclic oxidation is rather poor.Previous study has found that cyclic oxidation resistance of NiAl alloys and coatings can be drastically improved by minor Dy doping as reactive element.In this paper,NiAlDy alloys were produced by vacuum arc-melting and the effects of various Dy contents on the microstructure and hardness of NiAl alloys were investigated.The results suggest that Dy tends to segregate at grain boundaries and precipitate within grains as brittle DyNi2Al3 phase with little DyNiAl needles in it.The addition of minor Dy resulted in grain refinement.The grain size of NiAl alloy were reduced from ~1 mm to ~300 μm,with increasing the content of Dy to 0.5 at.%.The addition of ~0.1 at.% Dy caused a 10 %improvement in both the microhardness and macrohardness due to Dy solid-solution and grain-boundary segregation,but the alloy revealed decreased microhardness and macrohardness with further increasing the content of Dy to 0.5 at.% as the formation of Dy-rich phase.
Dysprosium (Dy) NiAl Reactive elements Strengthening Microhardness Macrohardness
Zhiyang Zhang Hongbo Guo Hui Peng Shengkai Gong Huibin Xu
School of Materials Science and Engineering, Beihang University, No.37, Xueyuan Road,Beijing 100191, China
国际会议
the Chinese Materials Congress 2012(2012年中国材料大会(CMC2012))
太原
英文
788-796
2012-07-13（万方平台首次上网日期，不代表论文的发表时间）