The effects of rare earth yttrium with different content on the degassing efficiency

corrosion resistance and hardness of the A356 alloy were investigated by rapid hydrogen gauge

intergranular corrosion

optical microscopy and hardness testing.The results show that the proper content of rare earth yttrium can purify effectively the alloy melt and reduce the hydrogen content in alloy melt and porosity.The proper amount of rare earth yttrium can improve the corrosion resistance and hardness of the alloy

however

the mechanical properties of the alloy are decreased with the excessive addition of Y.When rare earth yttrium addition is 0.3%

the hydrogen content in alloy melt is 0.16 mL/100 g Al

which is decreased by 56% compared with that of ones without Y addition

and the hardness is increased to 73 HB

increased by about 40%.Corrosion testing reveals that with 0.3%rare earth yttrium addition

the corrosion resistance of the A356 alloy is improved significantly

and absence of obvious corrosion pit on the surface layer can be observed

and the corrosion depth reaches approximately 145μm.Compared with that of ones without rare earth yttrium addition

the corrosion depth is decreased by 56%.