Consolidation behaviour of Cu/AlN composites by pulse electric current sintering of copper-coated aluminium nitride precursors

The effect of densification rate on hot consolidation behaviour by pulse electric current sintering (PECS) of AlN-Cu core-shell composite powders (approximate to 13 vol% Cu) is investigated. The ceramic phase was limited to 10, 20 and 30 vol% AlN by adding electrolytic copper particles. The Cu-coating on the ceramic surfaces served as a bridge for the passage of direct current to and between the copper particles of the matrix, making its conversion into heat more efficient. A constant pressure of 50 MPa was applied at the maximum of 850 degrees C. Three stages of displacement under load were observed, corresponding to particle rearrangement, localized deformation and deformation of the bulk. Thermal softening of the coating promoted a rapid surface-diffusion sintering and neck growth with the copper matrix, reaching a relative density above 97%. The Cu-coated particles led to a more homogeneous interconnected matrix microstructure and isolated the direct-contact between the ceramic particles. (C) 2020 Elsevier B.V. All rights reserved.