Synthesis and mechanical properties of Al₈B₄C₇

Abstract

Aluminum boron carbide (Al₈B₄C₇) was synthesized by heating a mixed powder consisting of Al:B₄C:C = 8:1:6 (molar ratio) at 1600°C for 1 h. The synthesized Al₈B₄C₇ powder was ball milled for 24 h with alumina balls to prepare an Al₈B₄C₇ powder with under 40 μm diameter. The fine Al₈B₄C₇ powder was then put into a carbon die, pressed, and sintered using PECS at 1650°C for 10 min under an applied pressure of 60 MPa, resulting in an Al₈B₄C₇ body with a relative density of 99.6%. The bending strength, Vickers hardness, and fracture toughness of the dense Al₈B₄C₇ body were 500 MPa, 15.2 GPa and 2.3 MPa·m^1/2, respectively. The bending strength of the dense Al₈B₄C₇ body increased during heating to 510 MPa at 1000°C, but decreased to 440 MPa at 1200°C.