Structural-phase state of polymetal AA5356-Mo produced by electron beam additive manufacturing

Al-Mo-based alloys are potential high-temperature materials because of their high melting point, high mechanical properties, and good thermal stability. However, the structural-phase state and the related mechanical characteristics of Al-Mo alloys are currently being actively studied because they strongly depend on the method of their production. In the present work, the possibility of obtaining AA5356-Mo polymetal by the combined production of AA5356 aluminum wire and 1.2 g/layer Mo powder by electron beam feed. It was found that the heterogeneous zone of AA5356-Mo polymetal is characterized by a complex and heterogeneous structure consisting of particles of unreacted Mo and the formation of Al-Mo phases of various types and morphologies. It was established that in the AA5356-Mo heterogeneous zone intermetallic phases Al₁₂Mo, A₁₅Mo, Al₈Mo₃ and supersaturated solid solution Mo(Al) are formed. It was shown that when only the first Mo powder layer is applied followed by AA5356 aluminum wire layer, partial precipitation of Mo powder and impurity elements on the earlier AA5356 layers is observed, which leads to the formation of a clear boundary of ∼5 µm thickness between the aluminum matrix and the AA5356-Mo heterogeneous layer.