Processing, microstructures, and properties of molybdenum aluminosilicide

Abstract

A ternary intermetallic compound-molybdenum aluminosilicide, Mo(Si0.8,Al0.2)2-was synthesized via micropyretic synthesis. The reaction constituents were elemental molybdenum, silicon, and aluminum powders in an atomic mixture of Mo + 1.6Si + 0.4Al. With the appropriate processing parameters, a highly dense product (up to 94% theoretical density) was obtained in a short time without applying external pressure. The synthesized product had a uniform microstructure, with a grain size of ∼16 μm. X-ray diffractometry and energy-dispersive spectroscopy confirmed the formation of Mo(Si0.8,Al0.2)2. In addition, small amounts of secondary phases (Mo5Si3 and Al2O3) were also identified in the product. The synthesized Mo(Si0.8Al0.2)2 was then subjected to various property measurements, including elastic moduli, Vickers hardness, indentation fracture toughness, and oxidation resistance. The measured property data, whenever possible, were compared to the corresponding values for MoSi2.