Abstract:The effect of homogenization time on quench sensitivity of a cast 7085 aluminum alloy was investigated by means of end-quenching test, optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that with the increase of homogenization time from 48 h to 384 h, quench sensitivity increased slightly as the largest difference in the hardness was increased from 5.2% to 6.9% in the end-quenched and aged specimens. Prolonging homogenization had little effect on the grain structure, but improved the dissolution of soluble T phase and resulted in larger Al₃Zr dispersoids with a low number density. Some small quench-induced η phase particles on Al₃Zr dispersoids were observed inside grains during slow quenching, which decreased hardness after subsequent aging. The change in the character of Al₃Zr dispersoids exerted slight influence on quench sensitivity.

Key words: 7085 aluminum alloy; homogenization; end quenching; quench sensitivity; Al₃Zr dispersoids; equilibrium η phase