| Considering the high yield strength and high ductility performance requirements for Cu matrix composites in the current applications, this paper prepared the in-situ TiCo.s particle reinforced Cu matrix composites by means of adding Ti2SnC ceramics as the poineer materials and studied the relevant technical and scientific problems in the Ti2SnC-Cu system. Regarding the reaction behaviors of Ti2SnC and Cu at high temperature, the in-situ TiC0.5 particle reinforced Cu(Sn) matrix composites were fabricated through hot-pressing. By X-ray diffraction (XRD), differential scanning calorimetry (DSC) analysis and scanning electron microscope (SEM) observation, the sintering parameters of the high purity Ti2SnC powders, the phase and the microsructure changes of Ti2SnC-Cu samples via different sintering processes, the microstructures and the compression properties of TiC0.5 particle reinforced Cu(Sn) matrix composites were explored. Meanwhile, the relationships among the fabrication processes, the microstructures and the compression properties of the composites were also studied.The results showed that:(1) The mole ratio of Ti/Sn/C, the sintering temperature and the heating rate had an influence on the purity of Ti2SnC powders. The results indicated that the purity of the Ti2SnC powders was highest after holding 2h in the vacuum when heating the Ti/Sn/C powders in the ratio of 2:0.9:0.85 to 1260℃ at the heating rate of 5℃/min.(2) The study on the reaction behaviors of Ti2SnC and Cu found that the mixed powders began to react while the temperature reached 900 ℃. Parts of Sn atoms in the Ti2SnC would escape and diffuse into the Cu matrix, leaving the TiC0.5 particles as reinforcements. The reaction would become severer as the temperature rise and the Ti2SnC phase decreased accordingly. When the temperature reached or exceeded the melting point of the Cu matrix, further reaction degree would occur due to the better liquid system.(3) In the TiC0.5/Cu(Sn) composites prepared by the reaction sintering of Ti2SnC and Cu at 1150℃, the micro scale Ti2SnC particles decomposed into sub-micro and nano size TiC0.5 particles. The TiC0.5 particles would distribute in the matrix uniformly. When the volume contents of Ti2SnC were 10%,20% and 30%, the initial Ti2SnC particles would almost decompose into TiC0.5 completely. For the 40% and 50% volume contents, some Ti2SnC still existed in the TiC0.5/Cu(Sn) composites.(4) The holding time had an influence on the microstructure of the TiC0.5/Cu(Sn) composites and the influence was related with the Ti2SnC volume contents. For the 10 vol.% Ti2SnC, the distribution of the TiC0.5 particle reinforcements in the matrix was not obvious. As the Ti2SnC volume content incresaed to 30%, the distribution of the TiC0.5 particle reinforcements in the matrix would become more and more homogeneous with a longer holding time. Respectively, the compression fracture strength and compression fracture strain of the TiC0.5/Cu(Sn) composites with 30 vol.% Ti2SnC were improved from 1109±11 MPa and 24.4±0.6% to 1260±22 MPa and 28.9±1.1% as the holding time increased from Oh to 2h.(5) The bulk density of the TiCo.s/Cu(Sn) composites decreased from 8.13 g/cm3 to 7.30 g/cm3 linearly with the volume content increase of Ti2SnC from 10% to 50%, while the Vickers hardness incresaed from 119.8±6.6 HV to 442.8±11 HV.(6) The TiC0.5/Cu(Sn) composites sintered at 1150℃ with the 2h holding time performed both high compression strength and high compression fracture strain. The compression yield strength enhanced from 150±12 MPa to 745±18 MPa as the Ti2SnC volume content increased from 10% to 50%. The compression fracture strength of the TiC0.5/Cu(Sn) composites with the 30 vol.%,40 vol.% and 50 vol.% Ti2SnC reached 1260±22 MPa,1448±4 MPa and 1587±16 MPa, separately. The corresponding compression fracture strains were 28.9±1.1%,17.7±0.7% and 8.3±1.5%. |
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