Study On In-suit Synthesis Of TiC_x Reinforced Ni Matrix Composites And Their Properties

Particle reinforced Ni matrix composites have the advantages of isotropic,easy molding,low cost and wide application range,etc.And the TiC_x reinforced Ni matrix composites prepared by in situ synthesis have many benefits,for instance,strong combination of particles and matrix,low porosity and no obvious impurities and so on,which has become the hotspot of the current research.In this paper,based on the improvement of strength and toughness,abrasion resistance and oxidation resistance of particle reinforced Ni matrix composites,the use of Ti₃SiC₂ ceramics as precursor materials are prone to the topological reaction to prepare in-suit synthesis of TiC_x reinforced Ni matrix composites by solid state diffusion method.The microstructures,mechanical properties,abrasion resistance and oxidation resistance of TiC_x reinforced Ni matrix composites were studied.Furthermore,the failure mechanism was analyzed and discussed.The experimental results show:?1?Study on the reaction of Ti₃SiC₂ ceramics and metal Ni at high temperature: the interfaces of Ti₃SiC₂ ceramics and metal Ni are well bonded at 1200 ?,and there is obvious reaction layer on the interface,but this condition can not synthesize composite materials;At 1300 ?,the composite materials were formed by diffusion reaction and the microstructures of Ti₃SiC₂ ceramics and metal Ni in different volume ratios were also studied respectively.The results show: when the volume ratio of Ti₃SiC₂ and Ni is 2:1,the composites consist of TiC_x,Ni16Ti6Si7 ternary phase and Ni31Si12 and other Ni-Si compounds as the main phases,containing a small amount of Ni?Si?solid solution.When the volume ratio of Ti₃SiC₂ and Ni is 1:1,Ti₃SiC₂ completely converted into TiC_x due to the topological reaction.TiC_x particle reinforced Ni?Si?composites are prepared by in situ synthesis,and no other impurity phases are formed.?2?In-suit synthesis of TiC_x reinforced Ni matrix composites have the hardness value of 663 HV,the flexural strength of 1234.30 MPa ± 306.5 MPa,the flexural modulus of 147.63 kN·mm-2 ± 19.28 kN·mm-2.The three-point bending fracture morphology of the samples is observed by scanning electron microscopy?SEM?.It is found that the fracture form of the composites is mainly dominated by ductile fracture and accompanied with a little fraction of fracture surface morphology of brittle fracture.?3?The sliding friction and wear properties of in-suit synthesis of TiC_x reinforced Ni matrix composites under different loading were studied.At room temperature,wear loss and mass wear rate of the composites increase with the rising of load,but the magnitude of the increase is not large.Moreover,the signs of adhesion and plastic deformation on the wear surface are gradually aggravated with the increasing of loads.?4?The constant temperature oxidation performance of in-suit synthesis of TiC_x reinforced Ni matrix composites were investigated at 700 ??800 ??900 ?.At high temperature,the composites were oxidated for 20 h continuously and the oxidation kinetics curve is basically consistent with the parabolic law.And the parabolic constants at 700 ??800 ??900 ? are 1.51×10-4?7.07×10-4? 4.52×10-3 mg2·cm-4·min-1 respectively,the activation energy is 188.56 kJ·mol-1.The oxidation products of the samples mainly consist of TiO2,accompanied with a little fraction of NiO and SiO2.