Microstructure and Performance of a Three-Layered Al/7075–B4C/Al Composite Prepared by Semi Continuous Casting and Hot Rolling

Abstract

A three-layered composite material, consisting of an Al outer layer and a 7075-10 wt % B4C inner layer, was fabricated by semi-continuous casting and following a hot rolling process. The composite exhibits a clear layered structure with a good interfacial bond between layers. In the sessile drop experiment, the Al alloy melt dropped on the 7075-B4C composite at 650 °C, with the contact angle decreasing from 105° to 25° in 50 s, indicating that the infiltration and spreading both played important roles in the wetting process. In the inner layer, the reinforced B4C particles were distributed uniformly in the 7075 alloy matrix, and enhanced the average hardness of the inner layer to 163.4 HV, compared to that of the outer layer at 32.8 HV. The composite plate of 20 mm obtained the compression strength of 152 MPa. The electron probe microanalysis (EPMA) line scanning result showed that no harmful reaction or element diffusion occurred between B4C and the surrounding 7075 matrix. The B4C particles remained mechanically bonded into the matrix, and significantly reduced the bullet speed during the projectile impact test.