J. Mater. Sci. Technol. ›› 2022, Vol. 123: 60-69.DOI: 10.1016/j.jmst.2022.01.012

• Research Article • Previous Articles     Next Articles

Strengthening mechanism of B4C@APC/Al matrix composites reinforced with bimodal-sized particles prepared by hydrothermal carbonized deposition on chips

Yingjie Hea, Hongyu Xua,*(), Yang Liub,c, Yihan Chena, Zesheng Jia,*()   

  1. aSchool of Material Science and Chemical Engineering, Harbin University of Science and Technology, Harbin 150040, China
    bEnergy and Environment Engineering Institute, Nanchang Institute of Technology, Nanchang 330044, China
    cCollege of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, China


A B4C@amorphous carbon (APC)/Al matrix composite was fabricated by using hydrothermal carbonized deposition on chips (HTCDC) process and solid-state synthesis process. The microstructure and mechanical properties of the B4C@APC/Al matrix composite were investigated. After HTCDC process, nano-B4C particles (50 nm) and micron-sized B4C@APC core-shell spheres with a diameter of 2 µm were found in the composites. The microhardness of the micron-sized B4C@APC spheres is 1.66 GPa, which is greater than that of the α-Al matrix (1.06 GPa). Dislocation accumulation is observed around the micron-sized B4C@APC spheres, indicating that the micron-sized B4C@APC spheres have a strengthening effect on the α-Al matrix. Due to the formation of micron-sized B4C@APC spheres, the reinforcement of nano-B4C particles into the composites is transformed from single-sized particle enhancement to bimodal-sized particle enhancement. The strengthening mechanism for B4C@APC/Al matrix composites with bimodal-sized particles of nano-B4C and micron-sized B4C@APC spheres were analyzed, which includes thermal mismatch strengthening generated by the mismatch of coefficient of thermal expansion (CTE) between micron-sized B4C@APC core-shell spheres and α-Al matrix, Orowan strengthening produced by nano-B4C particles, Hall-Petch strengthening and load transfer strengthening produced by the bimodal-sized enhancement from nano and microspheres. A relationship model between the yield strength (YS) increment and the conversion rate (x) of micron-sized B4C@APC core-shell spheres was estimated.

Key words: Bimodal-sized particle enhancement, Micron-sized B4C@APC core-shell spheres, Al matrix composites, Strengthening mechanism