Features of Al-10Mo electron-beam produced master-alloy assimilation in liquid aluminum and AlSi9Cu3 alloy

Abstract

The work is devoted to the Al-10Mo electron-beam prepared master-alloy modifying phases dissolution and assimilation features determination. It is shown that the obtained master-alloy is characterized by uniform distribution and high dispersion of molybdenum aluminide particles. When studying the process of dissolving the master-alloy in pure aluminum, it was determined that the time of modification of the melt more than 20 minutes at a temperature of 740 ± 10 ° C leads to the most complete destruction of the original intermetallics Al22Mo5 and Al17Mo4 and the formation of smaller and evenly distributed particles Al5Mo and Al12Mo with dimensions about 2 μm. As the molybdenum content decreases, the dispersion of the modifying phases and the uniformity of their distribution increase. Increasing the temperature and exposure time do not improve the assimilation of the modifier. The Al-10Mo master-alloy, obtained in the conditions of electron-beam casting technology, has a number of characteristics that allow to consider it as more efficient and cost-effective, compared to known analogues. This is due to the much higher concentration of molybdenum in the modifier (10% wt.), as well as fine dispersion and uniform distribution of the modifying phases. The nonequilibrium composition of aluminides inherent in the ligatures obtained under these conditions contributes to their significant grinding and refining after addition into aluminum melts. The stoichiometry of the phases from Al22Mo5 and Al17Mo4 changes to Al12Mo, which serve as crystallization centers and have a size of about 1 μm, dissolves and changes. The example of industrial casting alloy AlSi9Cu3 shows complete and effective assimilation of the master-alloy in a short time of 5 minutes at a temperature of 740 ± 10 ° C. Such indicators are more economic, in comparison with standard industrial ones, for which both higher temperature of melt preparing ant longer lifetime in liquid state after modification are necessary. Keywords: master-alloys, Al-Mo, modifications, aluminum alloys, AlSi9Cu3, resource saving.