Experimental and thermodynamic study on interfacial reaction of B4C–Al6061 composites fabricated by stir casting process

Boron carbide (B4C) reinforced aluminum (Al) alloy composites containing continuous multi-interphases were successfully fabricated by stir casting process. The B4C/Al reaction zone, consisting of a continuous aluminum carbide (Al4C3)/titanium, chromium diboride ((Ti,Cr)B2) multi-layer with chemically attached magnesium oxide (MgO) and TiB2 precipitates was formed between the B4C/Al6061 interface during the stir casting process, and no coarse AlB2 or Al3BC precipitates were observed in either the B4C/Al6061interface or the Al6061 matrix. Thermodynamic study of the formation of these interphases, described using the calculated isothermal phase diagram, revealed that the experimental results were very consistent with the thermodynamic calculations, and also suggested possible quantitative compositions of B4C and Al6061 at the interface for forming the mentioned interphases. •Fabrication of B4C–Al6061 composites containing continuous multi-interphases using a stir casting process.•Formation of novel structures of continuous Al4C3/(Ti,Cr)B2 layer with attached TiB2 and MgO precipitates.•In good agreement with the experimental and thermodynamic results (Al–Mg–Ti–B–O2–C system).•Study on the formation mechanism and quantitative compositions of interfacial microstructure of B4C–Al6061 composites.