In-situ synthesis of co-continuous aluminum-aluminum nitride composites by arc plasma induced accelerated displacement reaction

Abstract

We investigate in-situ formation of co-continuous aluminum (Al)-aluminum nitride (AlN) composites with attractive mechanical and thermal properties by newly developed arc plasma-induced accelerated displacement reaction (APADR). The core innovation of the process is that it combines a simple pressureless infiltration with a thermodynamically favorable displacement reaction of silicon nitride (Si3N4) and molten Al under arc-plasma induced ultra-high temperature. The fast volume displacement nitridation via APADR resulted from improved wettability and enhanced diffusion of dissolved nitrogen. Thus, within a minute of APADR, Al matrix composites (AMCs) containing AlN over 50 vol% were successfully fabricated by the infiltration of Al melt into Si3N4 particulate preforms with different particle size distributions. The microstructures of the composites exhibited co-continuous three-dimensional network structures with strong interfacial bonding and high interfacial thermal conductance, which resulted in a unique combination of relatively high flexural strength and high thermal conductivity. In particular, the AMCs containing nitrides of 73 vol% exhibited a low coefficient of thermal expansion, close to that of GaAs or GaN used for high-power semiconductor devices, which is the lowest value ever reported among the nitride reinforced AMCs. These results would give us a promising strategy for in-situ processing routes to fabricate continuous nitride reinforced AMCs with high dimensional and mechanical stability for heat spreader applications.