Effect of Al-5Ti-B₄C-Y refiner on the microstructure and properties of Al-Cu-Mn alloy

Al-5Ti-B₄C-Y refiner was prepared using Al-Ti, B4C powers and Al-Y as raw materials with vacuum arc furnace, and its effects on the microstructures and properties of Al-Cu-Mn alloy were studied. In order to explain the role of C and Y elements, the Al-5Ti-B and Al-5Ti-B-Y were also prepared as the reference grain refiners. Comparing the microstructures of these three grain refiners, it indicated that the C and Y elements could improve the dispersity of the TiB₂ particles, Y could modify the coarse needle-like Al₃Ti phases into blocky-like and the average sizes of the second phase particles in the Al-5Ti-B₄C-Y were the smallest. The microstructure of the Al-Cu-Mn alloy refined by these three grain refiners were investigated, and the results indicated that the Al-5Ti-B₄C-Y refiner shows the best refining efficiency and could modified the coarse dendrite crystal into equiaxed crystal. The ultimate tensile strength of the Al-Cu-Mn alloy refined by Al-5Ti-B₄C-Y reach 506 MPa, the yield strength reach 344 MPa and the elongation was increased to 12.9%. (paper)