Effect of Si on aging behavior and precipitated phase structure of Al-Er alloy
Effect of adding different amounts of Si on aging behavior and precipitated phase structure of the Al-Er alloy at different temperatures was studied by means of microhardness testers,conductivity testers and transmission electron microscopy.The results show that there is no obvious aging strengthening phenomenon during the aging process of the alloy when the Si content is 0.15%and 0.25%.The aging strengthening effect of the alloy is the best when the Si content is 0.50%,the hardness peak(about 40.3 HV0.1)is reached after 72 h of isothermal aging at 275℃and then rapidly decreases,and over aging occurs.During the aging,the desolvated solute atoms are the most from the Al-0.04Er-0.50Si alloy matrix,forming more precipitated phases,improving the hardness of the alloy,and increasing the conductivity by 4.0%IACS.After isothermal aging treatment,the number density of precipitated phases in the Al-0.04Er-0.50Si alloy is greatly increased,and the precipitated phase structure is no longer Al3 Er phase with L12 structure in the Al-Er alloy,but ErAl2.8Si0.2(τ1)phase with PuAl3(HT)type structure.
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