The Influence of Solution Treatment Time and Quench Rate on Microstructure and Mechanical Properties of High-Magnesium Aluminum-Magnesium Alloys.

Aluminum alloys containing 8-10 wt pct magnesium with further minor additions of Cu and Mn were solution treated for either 10 hours or 24 hours and subsequently quenched in either oil or water. Microstructural analysis by transmission electron microscopy and optical microscopy demonstrated that a 24-hour solution treatment when followed by water quenching was effective in retention of Mg in solution promoting more uniform precipitation during subsequent warm rolling, especially in an alloy containing 8.14 wt pct Mg-0.41 wt pct Cu. Tension and fatigue testing revealed improved fatigue resistance for this alloy when comparison was made to shorter solution treatment times and less severe quench conditions. The addition of Mn, possibly in conjunction with increased solution treatment temperature, appears to be especially effective in development of a homogeneous microstructure an alloy containing 10.2 wt pct Mg-0.52 wt pct Mn exhibited a yielded strength of 398 Mpa 57.8 Ksi, a tensile strength of 455 Mpa 75.8 Ksi with 11 pct elongation to fracture. Author