Increasing the Flow Stress during High-Temperature Deformation of Aluminum Matrix Composites Reinforced with TiC-Coated CNTs

Abstract

In this work, composites based on AA5049 aluminium alloy reinforced with multiwalled carbon nanotubes (CNTs) and multiwalled TiC-coated CNTs were prepared by powder metallurgy. For the first time, the effect of TiC coating on the CNT surface on the flow stress of aluminum matrix composites under compressive conditions at 300–500 °C has been investigated. It was found that composites reinforced with TiC-coated CNTs have a higher flow stress during high-temperature deformation compared to composites reinforced with uncoated CNTs. Moreover, with an increasing temperature in the 300–500 °C range, the strengthening effect increases from 14% to 37%. Compared to the reference sample of the matrix material without reinforcing particles, obtained by the same technological route, the composites reinforced with CNTs and CNT-hybrid structures had a 1.8–2.9 times higher flow stress during high-temperature deformation. The presented results show that the modification of the CNTs surface with ceramic nanoparticles is a promising structure design strategy that improves the heat resistance of aluminum matrix composites. This extends the potential range of application of aluminum matrix composites as a structural material for operation at elevated temperatures.

Control of Al4C3 phase formation in aluminum matrix composites reinforced with carbon nanostructures

“…Titanium, in contact with CNTs, resulted in the formation of TiC. The presence of a TiC interface on the surface of CNTs exhibited prominent barrier properties that prevented interfacial carbide formation reactions under elevated temperature conditions, as confirmed by recent work on high-temperature compression testing of AA5049 alloy-based composites reinforced with TiC/CNT nanostructures [40]. The presence of a TiC coating, with particle sizes ranging from 10-30 nm, on the surface of CNTs led to a 60% increase in deformation resistance at 500 °C compared to the composite reinforced with a similar weight fraction of untreated CNTs.…”

“…There are studies that highlight the prospects of modifying the surface of CNTs with various metals to prevent carbide formation reactions. For instance, in a study [40], composites based on AA2024 alloy were produced with hybrid reinforcement by adding 20% ABOw and 5% CNTs. When untreated CNTs were used, interfacial reactions between them and the aluminum matrix were observed.…”