Microstructure and mechanical behavior of AA2024/B4C composites with a network reinforcement architecture

Abstract

We reported an investigation of the influence of B4C contents on microstructure and mechanical behavior of AA2024/B4C composites. In our work, nearly full-dense AA2024/B4C composites with various B4C contents were fabricated by plasma activated sintering. Our results indicated that the B4C particles exhibit a network distribution in the composites with 7.5 wt % and 17.5 wt % B4C particles, adjacent particles of monolithic alloy are continuous or interpenetrated among the B4C particles in the powder boundary region. However, for the composite with 27.5 wt % B4C particles, the adjacent particles of monolithic alloy are interdicted due to the formation of severe aggregations. Improving the content of B4C particles will increase the hardness and compressive yield strength of the composites. However, the yield strength of the composite failed to be further improved when adding too much B4C because of the agglomeration of the reinforcements. With the content of 17.5 wt % B4C, the Vickers hardness and compressive yield strength of the consolidated composites were 203.2 HV and 564 MPa, respectively. In addition, quantitative analysis of the strengthening mechanisms revealed that increasing the weight fraction of the B4C particles results in larger augment in dislocation strengthening and load-bearing strengthening.