Effects of Yttrium Contents on Microstructures and Tensile Properties of Al-1%Mn Wrought Aluminum Alloy

The rare earth element (yttrium) with mass fraction of 0%, 0.07%, 0.21%, 0.31%, 0.38% in the form of Al-11%Y intermediate alloy was respectively introduced into the Al-1%Mn aluminum alloy, then the prepared alloy ingot was treated in the order of solid solution, hot rolling and cold rolling. The effects of yttrium contents on the microstructures of as-cast, hot rolled and cold rolled alloys, the tensile properties of cold rolled alloy and the hardness of as-cast alloy were studied. The results show that yttrium is an excellent modifier for Al-1%Mn alloy and the primary α-Al phases were refined from coarse dendrite to fine equiaxed grain after adding a certain content of yttrium. When the added yttrium content was about 0.31%, the grain refining effect was the most significant; the grain size of α-Al was reduced from 163.5 μm to 38.2 μm. Meanwhile, the tensile strength and elongation of the cold rolled alloy and the micro-hardness of the casting Al-1%Mn alloy with 0.31% yttrium increased from 267.62 MPa, 8.2% and 36.8 HV to 313.13 MPa, 14.8% and 39.42 HV respectively.