We conducted the study of viscosity liquid alloys AlMg6Li2(Sc) under the heating and subsequent cooling of samples. Results of these measurements allowed defining critical temperatures. The processing melt by heating above the critical temperature cause irreversible destruction of microinhomogeneities of hereditary nature. The irreversible destruction of micro-inhomogeneities improves the casting properties of the melts AlMg6Li2(Sc).Keywords: alloys Al-Mg-Li-Sc, microstructure, EDS-analysis, melt, viscosity, fluidity, temperature-time processing of melt
IntroductionThe alloys based on Al-Mg-Li system are being actively developed over the last years. Aluminum alloys containing lithium have a number of advantages in comparison with aluminum alloys based on other systems: their specific mass is averagely 10% lesser and the modulus of elasticity is 12% higher. Moreover, aluminum-lithium alloys can possess high mechanical characteristics (tensile strength reaches 600-650 MPa) with the good factors of crack resistance and corrosion resistance [1][2][3]. Despite all these advantages, AlMg6Li2 alloys are not widely used, mainly because of the low technological plasticity [4]. Reduced plasticity of annealed alloys with lithium is associated with high alloying and high volume ratio of phases compared to traditional alloys and also, to a lesser extent, with the incompleteness of recrystallization, reason for this is the large number of interfering particles Al3(Zr,Sc,Li)β'-phase [4][5]. Magnesium content has a strong influence on technological plasticity of annealed alloys of system Al-Li-Cu-Mg-Zr [5]. The studies have shown that annealing process at 400-530°Cfollowed by slow cooling results only in formation of phaseT2 (Al6CuLi3) [5]. The measurements of the lattice period allowed determining that nearly all of magnesium in alloy remains in solid solution after annealing, a small portion of it is included in T2-phase and precipitates under annealing. Reducing of plasticity of annealed alloys mainly correlates with the high content of magnesium in solid solution and also with increasing of T2-phase quantity. Structural studies have demonstrated [2,5] that the main reason for low plasticity of annealed alloys of this system is a big volume fraction of δ'-phase (Al3Li) particles not crossed by dislocations or β'-phase composite particles with δ'-phase shells. These particles larger than