Liquid matrix SHS manufacturing and heat treatment of Al–Mg composites reinforced with fine titanium carbide

Abstract

Aluminum matrix composites reinforced with ultra-fine refractory titanium carbide feature a unique combination of properties. They are promising structural materials. Self-propagating high-temperature synthesis (SHS) is an affordable and energy-saving composite making process. It involves the exothermic reaction between titanium and carbon (or their compounds) directly in the melt. We studied the properties of SHS composites based on the AMg2 and AMg6 commercially available alloys reinforced with 10 wt.%TiC. We investigated the macroand microstructure of the samples with XRD and EDS analysis. It was found that the β-phase is separated from α-solid solution of aluminum as early as the air cooling stage. We conducted experiments aimed at studying the effects of additional heating on the sample structure and properties and found the optimal temperature and time values. We also proposed a phenomenological model of the structural transformation sequence. We compared the physical, mechanical, and manufacturing properties and corrosion resistance of the original cold-hardened AMg2N and AMg6N alloys and the composites before and after heat treatment. It was found that additional heating reduces porosity and maintains electrical conductivity. It was also found that the compressive strength and relative strain of the composite based on the AMg2 alloy change insignificantly, while for the AMg6-based composite the reduction is more significant. Heat treatment increases the composite hardness while maintaining sufficient plastic deformation. It is confirmed by the measured values of the relative strain and the reduction ratio close to that of the original matrix alloys. It was also found that the composites retain high resistance to carbon dioxide and hydrogen sulfide corrosion.