Effect of Al-Sr-La intermediate alloy modification on microstructure and properties of A356 aluminum alloy
The Al-Sr-La intermediate alloy was used to modify A356 aluminum alloy,and the synergistic modification mechanism of Sr and La on microstructure and mechanical properties of the A356 aluminum alloy was studied.The results show that the addition of 0.5 mass%Al-Sr-La intermediate alloy has the best modification effect on the A356 aluminum alloy.At this time,the A356 aluminum alloy has excellent microstructure and mechanical properties,the grain size of α-Al phase is fine,the secondary dendrite arm spacing(SDAS)is reduced to 14.2 μm,which is 36.6%lower than that of the unmodified A356 aluminum alloy,and the needle-like eutectic Si phase transforms into worm-like eutectic Si with an average grain size of 0.86 μm.Compared with unmodified A356 aluminum alloy,the addition of 0.5 mass%Al-Sr-La intermediate alloy modification increases the tensile strength of the alloy by 22.4%,yield strength by 11.1%,and elongation by 89.7%.Finally,based on the experimental results and combined with solidification theory,the synergistic modification mechanism of Sr and La was studied.Sr adsorbs on the growth interface of Si phase,generating twin planes to suppress the growth of Si phase,causing Si to grow in twin plane reentrant(TPRE)mechanism,achieving modification of eutectic Si.Due to the effect of Sr on Si,La aggregates in the grooves of eutectic Si,hindering the growth of Si and improving the morphology of eutectic Si.
NETL
NSTL
万方数据
