新型细晶Ni_3Al涂层的制备及其循环氧化行为研究

Processing and cyclic oxidation of a novel fine-grained Ni_3Al coating

为提高γ'-Ni3Al合金氧化膜与基体间的粘结力,采用Ni与Al颗粒(平均粒径为1 um)共电沉积,然后600℃真空退火2 h的方法,在普通粗晶Ni3Al合金上制备了一种平均晶粒尺寸为450 nm,孔隙率为6%的Ni3Al涂层.与普通粗晶Ni3Al合金900℃下的循环氧化行为相比,Ni3Al细晶多孔涂层表面能形成一层粘附性良好的连续Al2O3膜,抗循环氧化性能显著提高,这主要是由于涂层的细晶结构避免了氧化时空位在Al2O3膜/基材界面沉积形成大尺寸孔洞,增加了Al2O3膜/基材界面结合强度.

To improve the adherence of the oxide scale formed on a γ＇-Ni3Al alloy,a novel Ni3Al fine-grained coating（average grain size： 450 nm） was developed by annealing an electrodeposited Ni-Al composite（average grain size of Ni and Al： 1 um） in a vacuum at 600℃ for 2h.The Ni3Al coating formed from common coarse grains had a homogeneous distribution of fine pores which gave a porosity of 6%.The cyclic oxidation resistance of the coating at 900℃ was greatly increased compared with that of a conventionally coarse-grained Ni3Al alloy（average grain size： 300 um） due to the formation of a continuous and adherent Al2O3 scale.The main reason for the increased scale adhesion lies in that the fine-grained structure improved the strength of the scale/coating interface by preventing the formation of large-sized voids.