Heat resistant properties of 2197 Al-Li alloy

The tensile properties at elevated temperatures and the room-temperature properties after long time thermal exposure of 2197 alloy were studied.Microstructures of 2197 alloy after long time thermal exposure at different temperatures were observed by TEM.The results show that the tensile strength at elevated temperatures decreases with increasing test temperature,and the tensile properties at 200 ℃ are higher than those of traditional aluminum alloy used at elevated temperature.After exposure at temperatures below 150 ℃ for 100 h,the mechanical properties of 2197 alloy increase slightly.This is related to the high coarsening resistance of T1 phase and secondary precipitation of θ′ phase at these temperatures.However,after exposure at 200 ℃ and 250 ℃ for 100 h,the mechanical properties of 2197 alloy decrease rapidly due to the dissolution of θ′ phase and rapid coarsening of T1 phase at these temperatures.