Effect of Y content on microstructure and mechanical properties of 2519 aluminum alloy

The effects of yttrium(Y) content on precipitation hardening, elevated temperature mechanical properties and morphologies of 2519 aluminum alloy were investigated by means of microhardness test, tensile test, optical microscopy(OM), transmission electron microscopy(TEM) and scanning electron microscopy(SEM). The results show that the tensile strength increases from 485 MPa to 490 MPa by increasing Y content from 0 to 0.10%(mass fraction) at room temperature, and from 155 MPa to 205 MPa by increasing Y content from 0 to 0.20% at 300 ℃. The high strength of 2519 aluminum alloy is attributed to the high density of fine θ′ precipitates and intermetallic compound AlCuY with high thermal stability. Addition of Y above 0.20% in 2519 aluminum alloy may induce the decrease in the tensile strength both at room temperature (20 ℃) and 300 ℃.