Investigation Of Sc, Zr And Ti Combination Alloying On The Microstructure And Mechanical Properties Of Al-5Mg Alloys

In this paper, eight kinds of Al-5Mg alloys with different scandium (Sc), zirconium (Zr) and titanium (Ti) content were produced by using pure aluminum, electrolytic low-titanium aluminum alloys, pure magnesium, Al-3Sc, Al-3Zr and Al-4.75Ti. The microstructure of these alloys were evaluated by using optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The room and high temperature tensile mechanical properties of these alloys were measured. The effect of complex alloying of Sc, Zr, and Ti on the microstructure, recrystallization resistance and mechanical properties of Al-5Mg alloys are investigated. The results are as following:The complex alloying of Sc- Zr, Sc-Ti or Sc-Zr-Ti make the grain refinement effect of alloys was obviously increased. Raising the Sc or Zr content can increase the refinement effect of grain. The alloys which alloyed with Sc, Zr and Ti have the optimum grain refinement effect. If titanium is added using low-titanium aluminum alloys to make the complex alloying of Sc, Zr and Ti, the grain refinement effect of alloys is obviously superior to that of alloys tradition titanium alloying method. The reason is that the complex alloys not only decreases the eutectic composition of Al-Al₃SC, which is favorite to the precipitation of prime complex particles from melt, but also a part of Sc can be replaced by Zr and Ti to form the Al3(Sc,Zr), Al₃(Sc,Ti) and even Al₃Zr_xTi_ySc_1-x-y complex particles, which make the particle have less size, higher disparity, homogeneous distribution and excellent discrepancy between lattice parameters. Increasing the Zr or Sc content can increase the volume fraction of complex particles. The homogeneous distribution of titanium in low-titanium aluminum alloys may enhance the complex alloying effect of Sc, Zr and Ti.Whether make the one component alloying with single Sc or complex alloying with Sc- Zr, Sc-Ti and Sc-Zr-Ti, the recrystallization resistance and room temperature and high temperature mechanical properties of Al-5Mg alloys are evidently increased Compared with common Al-5Mg alloys without Sc, the recrystallization temperature...