Thermally activated reactions of multi-walled carbon nanotubes reinforced aluminum matrix composite during the thermal spray consolidation

► The interfacial reactions of MWCNT reinforced Al composite in the HVOF spraying process are investigated. ► The MWCNTs reacted with oxygen at their defect sites, and were gasified into carbon oxide gas. ► A reaction between Al and carbon produced Al4C3 at the defect sites on the MWCNT surface. ► These reactions result in the deterioration of the reinforcement in the composite. ► The interfacial reaction mechanisms of the MWCNTs are discussed based on microstructural and thermodynamic analysis.