Effect of Re content on microstructure and mechanical properties of TiCN-WC-HfN ceramics
TiCN-WC-HfN ceramics were prepared by vacuum hot pressing sintering technology,and the effects of Re contents(molar fraction)on the microstructure and mechanical properties of the ceramics were investigated.The results show that,the TiCN-WC-HfN-Ni-Re ceramics are composed of TiC0.41N0.5,WC,HfN,TiC,Ni and Re,and TiC0.4N0.50 is the solid solution formed between TiC and TiN in the sintering process.Micro-pits and cleavage planes are discovered in the fracture surface of TiCN-WC-HfN ceramics with the different molar fraction of Re.When the molar fraction of Re is 2.5%,there are more micro-pits on the ceramic fractures.When the mole fraction of Re increases from 0 to 3.0%,the Vickers hardness,flexural strength,and fracture toughness of the TiCN-WC-HfN ceramics first increase and then decrease.When the mole fraction of Re is 2.5%,the mechanical properties of the ceramics show the best as the Vickers hardness is(19.25±0.21)GPa,bending strength is(1304±23)MPa,and fracture toughness is(7.73±0.22)MPa∙m1/2.Transgranular fracture and intergranular fracture of the TiCN-WC-HfN-Ni-Re ceramics occur during the fracture process,and the toughening mechanisms are the crack deflection and crack bridging.
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