Melting point depression of tin nanoparticles embedded in a stable alpha-alumina matrix fabricated by ball milling

Ball milling of SnO2 and Al powders creates Sn nanoparticles embedded in a stable α-Al2O3 phase through a displacement reaction. The production of stable α-Al2O3 phase indicates that sufficient thermal energy was supplied by ball milling to activate the displacement reaction. Melting points of Sn nanoparticles were observed to decrease with reducing particle size. The interfacial energy of solid tin particle-matrix was computed to be larger than liquid tin particle-matrix one. This is due to the formation of incoherent Sn-Al2O3 interfaces by ball milling. •Sn nanoparticles embedded in a stable α-Al2O3 phase are generated by ball milling.•Sn nanoparticles are created through a displacement reaction.•The melting points of Sn nanoparticles vary with the inverse of their sizes.•Incoherent and high energy Sn-Al2O3 interfaces cause melting point depression.