Mechanical Properties And Three-Dimensional Finite Element Simulation Of B₄Cp/6061Al Composites

Compared with pure aluminum or aluminum alloys,particle reinforced aluminum matrix composites(PRAMCs)have excellent comprehensive properties such as high strength,high specific modulus,wear resistance,high temperature resistance,and good designability,and thus have been widely used in military and civil fields.B₄Cp/Al composites,viewed as a kind of PRAMCs,have attracted extensive attention due to their low density and neutron shielding ability.During the transportation of spent fuels,B₄Cp/Al composites may be subjected to external force due to the impact or bump effect.Therefore,it is very important to evaluate the mechanical properties and failure behavior of B₄Cp/Al composites.In general,it is difficult to characterize the internal deformation and damage information of materials by conventional experimental methods,however,the establishment of real finite element simulation method can effectively solve this tough issue.In this work,10 wt%B₄Cp/6061Al composites were prepared by powder metallurgy(PM).The selected B₄C particle sizes were?20?m,?50?m and?80?m,respectively.The microstructure of the composites was quantitatively analyzed by synchrotron radiation computed tomography,and the finite element model based on the real three-dimensional structure was established to simulate the uniaxial tensile process of the composites.Combined with the tensile test and simulation results,the deformation and damage process of B₄Cp/6061Al composites were explored,and the effect of particle size on the mechanical behavior of the composites was elucidated,which provides a theoretical basis for the preparation,structural design,and performance control of PRAMCs.The results show that the particles are well dispersed in the matrix,and there is no obvious interface product in the composites prepared by PM.The density of the composites is close to the theoretical density.Cracks can be observed in some B₄C particles.With the increase of particle size,the proportion of particles with cracks increases.Synchrotron radiation imaging experiment is used to analyze the voids in the composites.The voids are mainly located at the sharp corner of B₄C particles and near the interface of B₄C particles aggregation.Quantitative analysis shows that with increasing the particle size,the voids around B₄C particles become large,and the total volume of voids increases,resulting in a decrease in relative density of the composites.In terms of mechanical properties,as the particle size increases,the yield strength,tensile strength and elongation of the composites decrease.The plastic deformation ability of the matrix decreases obviously,and the dimples of the matrix on the fracture surface become shallow.The particles containing cracks can be observed in the fracture surface.Compared with the statistical results before tensile,the proportion of cracks in the?80?m particles is the highest.At the same time,the interface deboning between the particles and matrix can be found on the fracture surface.Based on the results of synchrotron radiation imaging,a real three-dimensional finite element model is established,and the simulated tensile curves are in line with the experimental results.Compared with the yield strength increment obtained by only using the microstructure strengthening formula,the simulation results of yield strength are closer to the experimental results.The stress on the particles is mainly concentrated at the sharp corners and recesses of the particles,and the strain in the matrix is related to the particle distribution.When the particle size increases,the stress on particle and interface is low,which leads to the early occurrence of particle fracture and interface debonding due to the low damage strength.This causes the decrease in bearing capacity of the particles.The fractured particles and damaged interfaces act as the initial cracks.The cracks propagate towards the high strain regions in the matrix,and finally form the main cracks.In addition,the particle fracture,interface deboning,and ductile fracture of matrix are observed on the simulated tensile fracture surface,which is in accordance with the experimental result.