Improving oxidation resistance property of single-crystal Ni-based superalloy via utilizing high temperature aging-induced dislocations
Boxuan Du, Yi Ru, Jiao Wen, Xuetao Li, Yang Cao, Yunpeng Hu, Fan Yang, Yanling Pei, Shusuo Li, Shengkai Gong
Abstract
It is hard to improve the oxidation resistance property of single-crystal (SC) Ni-based superalloys except for alloying design since monocrystalline lacks defects such as grain boundaries that are beneficial for antioxidant elemental diffusion. This work indicates that dislocations in SC superalloys have a beneficial effect on oxidation resistance. These dislocations are formed via high-temperature aging. Taking advantage of such dislocations, the sample aged exhibited an extremely low oxidation rate, and a protective α-Al 2 O 3 layer formed rapidly at the surface instead of multilayer oxides without the aid of aging dislocations, determining the change in oxidation mechanism. The atomic-scale investigation revealed that the Al had a higher activity in aged specimens, and the dislocation from aging treatment enabled the pipe diffusion effect. Based on our results, a new route to improving oxidation resistance of SC superalloys is proposed as skilled designing of dislocations acting as Al-diffusion pipes. These findings give a new insight into recently popular “crystal defect engineering” of alloys and provide guidelines for oxidation resistance improvement of superalloy and other alloys.