Thermal conductivity and interfacial conductance of AlN particle reinforced metal matrix composites

Aluminum nitride (AlN) particle reinforced metal-matrix-composites produced by pressure infiltration are characterized in terms of their thermal conductivity. The composites are designed to cover a wide range of phase contrast between the dispersed particles and the matrix; this is achieved by changing the matrix conductivity using Cu, Al, Sn, and Pb as the matrix. The interface thermal conductance (h(c)) between AlN and the matrix metals is determined by varying the size of the AlN particles using the Hasselman-Johnson approach and the differential effective medium (DEM) model to calculate h(c) from measured composite conductivity values. In addition, h(c) is measured directly at the AlN/Al interface using the transient thermoreflectance (TTR) method on thin aluminum layers deposited on flat AlN substrates to find good agreement with the value derived directly from Al/AlN composites of variable particle size and thus confirm the approach used here to measure h(c). Data from the study show that h(c) at AlN-metal interfaces increases with the metal/AlN Debye temperature ratio; however, the increase is much less than predicted by currently accepted models. (C) 2011 American Institute of Physics. [doi:10.1063/1.3553870]