The effects of temperatures on microstructure evolution and mechanical properties of B4C–AA2024 composite strips prepared by semi-solid powder rolling

Abstract

Semi-solid powder rolling (SSPR) is a novel method to prepare metal strips, which combines the advantages of powder rolling and semi-solid forming. Besides, it is a near-net shape forming with high efficiency and energy saving. 10% B4C–AA2024 composite strips with the relative density of 0.75–0.95 were prepared by SSPR. The effects of temperatures on the microstructures, brinell-hardness and tensile strength of B4C–AA2024 composite strips were analyzed. The laws of microstructure evolution and densification were discussed. The results show that the best liquid fraction to prepare a 10% B4C–AA2024 composite strip ranges from 38% to 60%. The liquid phases in the powders exist in the form of isolated melt pools when liquid fraction is lower than 20%. When liquid fraction is higher than 20%, liquid phases forms a fluid network, lapping mutually or filling in the pores among the powders. Liquid phases play an important role in the formation of microstructures. B4C particles can restrain the generation of micro-cracks during the solidification process.