What effect does yttrium have on the Al-Cu-Mg-Mn alloy?>

 As we you know, aluminum alloys are widely used in military and civil applications as it’s lightweight materials among metal materials. Among them, Al-Cu-Mg alloys are widely used in aircraft structures, rivets and other high-temperature-resistant structural parts due to their strength and high temperature resistance. Manganese in Al-Cu-Mg alloys can improve the alloy's corrosion resistance, neutralizing the harmful effects of iron, and also control grain size and inhibit recrystallization, thereby increasing the high temperature strength of the alloy. Research shows that rare earth yttrium have a positive effect on the strength and creep resistance of aluminum alloys . Adding an appropriate amount of rare earth yttrium element to aluminum and aluminum alloys can purify alloy melts, refine grains, strengthen alloys and improve corrosion resistance, and can also improve the high temperature properties of alloys.

A team from China has studied the addition of different contents of yttrium element to the Al-Cu-Mg-Mn alloy, and observed the existence of yttrium in the alloy and its influence on its microstructure and properties.They added the Al-Y10 master alloy to the alloy for this research.

The research shows that the as-cast microstructure is refined and more uniform after adding an appropriate amount of aluminium yttrium master alloy to the Al-Cu-Mg-Mn alloy, and the addition of yttrium to the Al-Cu-Mg-Mn alloy forms a new Cu4Al8Y phase with Al and Cu.

When the addition amount of rare earth yttrium is 0.3 %, the effect of refining the as-cast structure and the morphology of the second phase is the most obvious. When the addition amount of Y continues to increase, the phenomenon of grain coarsening appears instead.

Also the addition of yttrium element can improve the strength and hardness of the Al-Cu-Mg-Mn alloy. When the addition is excessive, yttrium forms a compound with the elements in the alloy, which reduces the precipitation of the aging phase S (A12CuMg), thereby reducing the mechanical properties.