Preparation and microstructure of Cu-Al2O3 composites by a novel supercritical water liquid phase in-situ reaction method

Abstract

The high solubility, reactivity and solubility of supercritical water provide a new way for the preparation of advanced metal matrix composites. In this paper, Cu-Al2O3 composites are prepared by supercritical water liquid phase in situ reaction (SW-LIR). In this method, the Cu-Al atomized alloy powder are used as raw material, deionized water as reaction medium, H2O2 as liquid phase oxygen source, and the Cu-Al2O3 composite powder are prepared at 380 ℃ and 22.1 MPa for 10 min. The Cu-Al2O3 composite block is prepared by spark plasma sintering (SPS). The results show that Al2O3 has an average size of 41.8 nm and mainly exists in the form of mixed crystals. The interface with the matrix is coherent or semi-coherent. With the increase of Al2O3 content, the mechanical properties of the composites are obviously improved. When the Al2O3 content is 1.12 wt%, the microhardness is as high as 164.52 HV and the tensile strength is 441 MPA, while still maintaining a high electrical conductivity (75 %IACS). At the same time, it shows quite excellent high temperature performance. It can still retain the characteristics of high strength at 1000℃, which solves the shortcomings of high thermal conductivity but low strength of pure copper. Compared with the traditional method, SW-LIR method has the characteristics of low reaction temperature, fast reaction speed and green environmental protection.