Fabrication And Dynamic Compression Properties Of Cu-riched Mo/Cu Composition With Three-dimensional Interpenetrating Micro-structure

Copper-riched molybdenum/copper(Mo/Cu) composites are promising materials for high-energy elector device and shaped charge liner materials due to its excellent ductility, prominent thermal and electrical properties. But the Mo generally exist in the form of particles or fibers for the traditional Cu-riched Mo/Cu composites, which limit the high strength performance of Mo and excellent ductility of Cu. In this study,Cu-riched Mo/Cu IPCs were successfully fabricated by metal infiltration process, in which porous Mo prepared by using spherical carbamide as space holders via powder metallurgy technology were used as the preforms. The effect of porosity and sintering temperature on the structure and compression properties of porous Mo skeleton and Mo/Cu IPCs were investigated. In addition, the strengthening and toughing mechanism as well as deformation process of the Mo/Cu IPCs was studied by comprehensive analysis of the experiment and model results.Herein the preferred forming pressure of cold isostatic pressing process for Mo skeleton is 300 MPa, and the sintering temperature is 1600 o C. The relative density of Mo/Cu IPCs prepared by infiltration reached 98.2%. The results of compression testing show that the strength of the porous Mo skeleton increases with the decrease of porosity, and the sintering temperature of the molybdenum skeleton influences the binding state of the particles and determines the strength of the skeleton. When the skeleton sintering temperature increases from 1200 oC to 1600 oC, the bonding state of Mo particles are improved and the compression strength of the porous Mo are increasing from 30 MPa to 60 MPa. Further increasing the sintering temperature to1800 o C would reduces its particle bonding strength, and decrease the strength of the skeleton.The structure of Mo/Cu IPCs inherited the structure of Mo skeleton, in which the Mo skeleton and the Cu are bridged with each other and formed a interconnected network. The IPCs shows excellent overall mechanical. With the increase of Mo skeleton porosity, the Cu content of Mo/Cu IPCs increased, and therefor the compression strength decreased and plasticity increased. Increasing the skeletonsintering temperature within certain realms induced the increase of Mo content and Mo/Mo contiguity, which increased the strength of Mo/Cu IPCs. The IPCs prepared by 1600 oC sintered Mo skeleton possess the highest hardness and strength.Further raise of sintering temperature(to 1800oC) are detrimental to the bonding of Mo particles and hence reduce the strength of Mo/Cu interpenetrating composite.It have been found that the self-connected Mo skeleton in IPCs can not only transfer the loading effectively but also bear most of loading. The large distribution of interface prevents the dislocation glide, as a result increases the yield strength; the excellent toughness of copper played a excellent crack bridging and deformation coordinating effect during compression loading. When the composition were subjected dynamic loading, the deformation of the material was instantaneous and inhomogeneous. Therefor the stress preference concentrated in the Mo skeleton,leading to the formation of shear crack. Due to the short time of deformation, the plastic flow of the copper in the IPCs was restrained, which induced three axis stress in the copper region leading to the generation of the crack.