Abstract
In this study,the oxidation behavior of Ti42Al5Mn,Ti42Al5Mn0.5 W,Ti42Al5Mn0.5W0.1B,and Ti42Al5Mn0.8 W was investigated at 800 ℃.Due to the inability to form a dense protective Al2O3 layer,Ti42Al5Mn suffered severe spallation during oxidation at 800 ℃ and the mass gain was significant.The intermediate layer between the scale and the substrate was first composed of Laves/Z phase but changed to α2/Z phase with prolonged oxidation.The intermediate layer with high Ti/Al ratio favors the forma-tion of a thick Al2O3+TiO2 mixed layer in the oxide scale which is prone to initiate cracks and cause the spalling of oxides.The doping of W in TiO2 effectively inhibited its generation and promoted the for-mation of a dense Al2O3 layer,resulting in a significant improvement in the oxidation resistance of the alloy.Compared to Ti42Al5Mn alloy,Ti42Al5Mn0.8 W showed no spallation after 300 h cyclic oxidation and the kinetic curve changed from liner law to parabolic law.The intermediate layer of Ti42Al5Mn0.8 W alloy was composed of a single Laves phase and remained unchanged even after 1000 h oxidation at 800 ℃,offering a favorable basis for the generation of a stable protective oxide layer in the alloy.The addi-tion of 0.1 at.％B to Ti42Al5Mn0.5 W alloy refined its microstructure and further improved its spallation resistance to a level close to that of Ti42Al5Mn0.8 W alloy.
基金项目
National Natural Science Foundation of China(51971215)
NETL
NSTL
万方数据