Enhanced interfacial wettability and mechanical properties of Ni@Al2O3/Cu ceramic matrix composites using spark plasma sintering of Ni coated Al2O3 powders

Abstract

Poor wettability and weak interfacial bonding between Cu and Al2O3 have been critical issues for sintering of high-quality Ni@Al2O3/Cu composites. In this paper, we explore an interfacial engineering design methodology to achieve good mechanical properties of Ni@Al2O3/Cu composites using spark plasma sintering method. The Ni coated powders were prepared using a heterogeneous precipitation method, which can significantly improve wettability between Cu and Al2O3 and enhance their interfacial bonding. The sintered Ni@Al2O3/Cu composites with a copper content of 15 vol% showed a compact network structure of alumina well-infiltrated with metallic Cu, and achieved good mechanical (e.g., fracture toughness of 6.72 MPam1/2) and physical properties (e.g., relative density of 99.3% and electrical resistivity of 1.2810−3 Ω m). The key mechanisms for the enhanced properties of the composites synthesized using the Ni coated composite powders have been identified as: (1) well-formed ceramic/metal interfacial structures which improve wettability of Al2O3 with Cu, and promote the formation of a homogeneous network structure; (2) enhanced elemental diffusion and interfacial reactions, which result in formation of Cu2O and CuAlO2 and thus improve interfacial wetting and bonding properties.