Self-Propagating High-Temperature Synthesis of (Al–2% Mn)–10% TiC and (Al–5% Cu–2% Mn)–10% TiC Nanostructured Composite Alloys Doped with Manganese Powder

Resumo

The influence of alloying with powder manganese on the preparation of nanostructured (Al‒2% Mn)–10% TiC and (Al–5% Cu–2% Mn)–10% TiC composite alloys with the application of the self-propagating high-temperature synthesis (SHS) of titanium carbide TiC nanoparticles from the Ti + C charge in a melt of matrix alloys is investigated. Powder metallic manganese in an amount of 2 wt % is preliminarily introduced into Al and Al–5%Cu matrix bases of composite alloys. This makes it possible to increase the ultimate tensile strength of the aluminum base from 81 MPa (for initial aluminum of the A7 brand) to 136 MPa and that of the aluminum–copper base to 169 MPa. It is revealed that, when alloying aluminum only with manganese, the SHS reaction proceeds weakly and incompletely, while the carbide phase size in the (Al‒2% Mn)–10% TiC alloy varies from a nanolevel to several microns. When adding 10% of the Na₂TiF₆ haloid salt into the SHS charge, the SHS process is intensified, but the resulting alloy contains numerous pores, inclusions of the unreacted charge, and coarse agglomerates of ceramic nanodimensional TiC particles. When using Ti + C and Ti + C + 10% Na₂TiF₆ SHS charges with coalloying matrix aluminum by copper and manganese, similar results are acquired. The difference is in the larger distribution uniformity of the nanodispersed TiC phase. The best results are attained with a decrease in the Na₂TiF₆ additive to 5% of the charge weight, which promotes the smoother and complete synthesis of preferentially nanodimensional TiC particles and the formation of the poreless homogeneous microstructure of the (Al–5% Cu–2% Mn)–10% TiC composite alloy with an ultimate tensile strength of 213 MPa and relative elongation of 6.6%.