| Copper-based composites have been widely concerned because of their low strength and poor heat resistance to copper and copper alloys.In copper matrix composites,various kinds of reinforcing phases are introduced into the matrix to obtain better comprehensive properties.In this project,Ti Ni particles with B2 parent phase at room temperature were selected as the reinforcing phase to explore the law of its influence on copper matrix composites.In this paper,Ti Ni/Cu composites were characterized by experimental research and finite element simulation.Obtained by vacuum hot-pressing sintering,the preparation of copper matrix composites,using X-ray diffraction(XRD),scanning electron microscope(SEM),differential scanning calorimetry(DSC)and analytical means such as electronic universal testing machine to strengthen body material and composite material performance testing,after using ABAQUS/CAE software builds finite element model of copper matrix composites,analyzed the Ti Ni reinforced copper matrix composite materials in the process of drawing the internal stress state,in order for the construction of the Ti Ni/Cu composites provides the reference and know.In terms of experimental research,the influence of ball grinding speed and ball grinding time on the mixed powder in the ball grinding process was firstly explored,and the optimal ball grinding process parameters were determined as the ball grinding speed of 200 rpm and ball grinding time of 3 h.Then,Ti Ni reinforced phases with different particle sizes were used to prepare copper-based composites,and their effects on microstructure,phase transition behavior and mechanical properties were investigated.The research results show that: for the composites prepared by vacuum hot pressing sintering,Ti Ni particle reinforcement and Cu will react to form a reaction layer,and the reaction layer Cu:Ti:Ni atom ratio is about 1:1:1.When the particle size was 15-53 ?m,the thickness of the reaction layer was about 10 ?m.When the particle size was 53-150 ?m,the thickness of the reaction layer was about 6 ?m.In addition,the one-step phase transition occurred between B2 and B19' in the process of lifting and cooling.When the larger Ti Ni particles were selected for reinforcement,the phase transition peak of the composite was more sharp,and the phase transition temperature was lower than that of the Ti Ni pre-alloying powder.The stress-strain curve showed that the tensile strength and elongation of Ti Ni with particle size of 15-53 ?m were higher than those of 53-150 ?m.In terms of simulation,finite element analysis software ABAQUS/CAE was usedto establish the finite element model of Ti Ni/Cu composites with uniform and random distribution of Ti Ni particles,and unidirectional tensile load was applied to simulate the distribution of stress field inside the composites under tensile stress.The influence of the shape of the reinforcing phase,the particle size,the volume fraction of the reinforcing phase and the distribution of the reinforcing phase on the stress field is analyzed.The simulation results show that when the shape of the reinforcing phase is sphere,ellipsoid,cube,cuboid and hexagonal prism respectively,the stress concentration generated by the reinforcing phase inside the material is the smallest and the reinforcement effect is the best,and the stress of the reinforcing phase is gradually transferred from the outside to the inside.By comparing the stress distribution of pure copper and Ti Ni/Cu composites,it is shown that the addition of Ti Ni particles can change the isotropy of copper matrix,and the stress distribution is uneven.Compared with pure copper,the mechanical properties of copper matrix reinforced by Ti Ni can be improved.When the particles are uniformly distributed,by comparing the stress fields of different Ti Ni particle sizes,it can be concluded that the smaller the Ti Ni particle size is,the greater the stress of the particles will be,and the better the strengthening effect of the material will be.By analyzing the different volume fraction of the Ti Ni particulate reinforced copper matrix composites,along with the increase of phase volume fraction,the increase in load bearing,enhancement effect for the materials,the better,but too much will make top and bottom row between particles volume fraction matrix is larger stress concentration,once more than concrete tensile strength and the failure will be there.When the particles are randomly distributed,similar to the uniform distribution,the smaller the Ti Ni particle size,the larger the volume fraction of the reinforcement phase,and the larger the load of the reinforcement phase,the better the mechanical properties of the material will be improved.By comparing the Ti Ni particle uniform distribution and random effect on mechanical properties of discovery: particle random distribution,may cause stress interference at close range for some particles lead to stress concentration,so the smaller particles generated when the uniform distribution of stress concentration,and higher mechanical properties,so try to use some technology to make particles uniformly distributed within the copper matrix. |
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