Effect of high heating rates on the melting behavior of embedded In nanoparticles

Stringe M, Rösner H, Wilde G

Abstract

In nanoparticles embedded in an Al-rich polycrystalline matrix have been investigated concerning the kinetics oftheir melting behavior. The advantage of the present system lies in the fact, that two distinct populations ofparticles are intrinsically formed: facetted nanoparticles that are embedded within the matrix grains and thatobey the facetted Wulff shape or slight deviations thereof and particles situated at the grain boundaries of thematrix that form curved interfaces with the matrix grains. This second fraction thus serves as an internal reference,since the particles at the grain boundaries melt at the bulk melting temperature. Utilizing an averagingprocedure for the fast scanning calorimetry measurements and combining conventional differential scanningandfast scanning calorimetry with microstructure investigations, we found strong evidence for the observationof a heating-rate dependence of the melting transformation of the matrix-embedded nanoparticles. This observationgives rise to discuss the kinetics of melting in cases where the most potent nucleant for melting, the surface, is deactivated.